diff --git a/framework-t/src/android/net/nsd/NsdManager.java b/framework-t/src/android/net/nsd/NsdManager.java
index 263acf2..27b4955 100644
--- a/framework-t/src/android/net/nsd/NsdManager.java
+++ b/framework-t/src/android/net/nsd/NsdManager.java
@@ -159,6 +159,8 @@
                 "com.android.net.flags.nsd_subtypes_support_enabled";
         static final String ADVERTISE_REQUEST_API =
                 "com.android.net.flags.advertise_request_api";
+        static final String NSD_CUSTOM_HOSTNAME_ENABLED =
+                "com.android.net.flags.nsd_custom_hostname_enabled";
     }
 
     /**
@@ -1237,7 +1239,7 @@
      */
     public void registerService(@NonNull NsdServiceInfo serviceInfo, int protocolType,
             @NonNull Executor executor, @NonNull RegistrationListener listener) {
-        checkServiceInfo(serviceInfo);
+        checkServiceInfoForRegistration(serviceInfo);
         checkProtocol(protocolType);
         final AdvertisingRequest.Builder builder = new AdvertisingRequest.Builder(serviceInfo,
                 protocolType);
@@ -1296,7 +1298,10 @@
      * @return Type and comma-separated list of subtypes, or null if invalid format.
      */
     @Nullable
-    private static Pair<String, String> getTypeAndSubtypes(@NonNull String typeWithSubtype) {
+    private static Pair<String, String> getTypeAndSubtypes(@Nullable String typeWithSubtype) {
+        if (typeWithSubtype == null) {
+            return null;
+        }
         final Matcher matcher = Pattern.compile(TYPE_REGEX).matcher(typeWithSubtype);
         if (!matcher.matches()) return null;
         // Reject specifications using leading subtypes with a dot
@@ -1327,10 +1332,7 @@
             @NonNull RegistrationListener listener) {
         final NsdServiceInfo serviceInfo = advertisingRequest.getServiceInfo();
         final int protocolType = advertisingRequest.getProtocolType();
-        if (serviceInfo.getPort() <= 0) {
-            throw new IllegalArgumentException("Invalid port number");
-        }
-        checkServiceInfo(serviceInfo);
+        checkServiceInfoForRegistration(serviceInfo);
         checkProtocol(protocolType);
         final int key;
         // For update only request, the old listener has to be reused
@@ -1607,7 +1609,7 @@
     @Deprecated
     public void resolveService(@NonNull NsdServiceInfo serviceInfo,
             @NonNull Executor executor, @NonNull ResolveListener listener) {
-        checkServiceInfo(serviceInfo);
+        checkServiceInfoForResolution(serviceInfo);
         int key = putListener(listener, executor, serviceInfo);
         try {
             mService.resolveService(key, serviceInfo);
@@ -1661,7 +1663,7 @@
     // TODO: use {@link DiscoveryRequest} to specify the service to be subscribed
     public void registerServiceInfoCallback(@NonNull NsdServiceInfo serviceInfo,
             @NonNull Executor executor, @NonNull ServiceInfoCallback listener) {
-        checkServiceInfo(serviceInfo);
+        checkServiceInfoForResolution(serviceInfo);
         int key = putListener(listener, executor, serviceInfo);
         try {
             mService.registerServiceInfoCallback(key, serviceInfo);
@@ -1706,7 +1708,7 @@
         }
     }
 
-    private static void checkServiceInfo(NsdServiceInfo serviceInfo) {
+    private static void checkServiceInfoForResolution(NsdServiceInfo serviceInfo) {
         Objects.requireNonNull(serviceInfo, "NsdServiceInfo cannot be null");
         if (TextUtils.isEmpty(serviceInfo.getServiceName())) {
             throw new IllegalArgumentException("Service name cannot be empty");
@@ -1715,4 +1717,46 @@
             throw new IllegalArgumentException("Service type cannot be empty");
         }
     }
+
+    /**
+     * Check if the {@link NsdServiceInfo} is valid for registration.
+     *
+     * The following can be registered:
+     * - A service with an optional host.
+     * - A hostname with addresses.
+     *
+     * Note that:
+     * - When registering a service, the service name, service type and port must be specified. If
+     *   hostname is specified, the host addresses can optionally be specified.
+     * - When registering a host without a service, the addresses must be specified.
+     *
+     * @hide
+     */
+    public static void checkServiceInfoForRegistration(NsdServiceInfo serviceInfo) {
+        Objects.requireNonNull(serviceInfo, "NsdServiceInfo cannot be null");
+        boolean hasServiceName = !TextUtils.isEmpty(serviceInfo.getServiceName());
+        boolean hasServiceType = !TextUtils.isEmpty(serviceInfo.getServiceType());
+        boolean hasHostname = !TextUtils.isEmpty(serviceInfo.getHostname());
+        boolean hasHostAddresses = !CollectionUtils.isEmpty(serviceInfo.getHostAddresses());
+
+        if (serviceInfo.getPort() < 0) {
+            throw new IllegalArgumentException("Invalid port");
+        }
+
+        if (hasServiceType || hasServiceName || (serviceInfo.getPort() > 0)) {
+            if (!(hasServiceType && hasServiceName && (serviceInfo.getPort() > 0))) {
+                throw new IllegalArgumentException(
+                        "The service type, service name or port is missing");
+            }
+        }
+
+        if (!hasServiceType && !hasHostname) {
+            throw new IllegalArgumentException("No service or host specified in NsdServiceInfo");
+        }
+
+        if (!hasServiceType && hasHostname && !hasHostAddresses) {
+            // TODO: b/317946010 - This may be allowed when it supports registering KEY RR.
+            throw new IllegalArgumentException("No host addresses specified in NsdServiceInfo");
+        }
+    }
 }
diff --git a/framework-t/src/android/net/nsd/NsdServiceInfo.java b/framework-t/src/android/net/nsd/NsdServiceInfo.java
index ac4ea23..146d4ca 100644
--- a/framework-t/src/android/net/nsd/NsdServiceInfo.java
+++ b/framework-t/src/android/net/nsd/NsdServiceInfo.java
@@ -49,8 +49,10 @@
 
     private static final String TAG = "NsdServiceInfo";
 
+    @Nullable
     private String mServiceName;
 
+    @Nullable
     private String mServiceType;
 
     private final Set<String> mSubtypes;
@@ -59,6 +61,9 @@
 
     private final List<InetAddress> mHostAddresses;
 
+    @Nullable
+    private String mHostname;
+
     private int mPort;
 
     @Nullable
@@ -90,6 +95,7 @@
         mSubtypes = new ArraySet<>(other.getSubtypes());
         mTxtRecord = new ArrayMap<>(other.mTxtRecord);
         mHostAddresses = new ArrayList<>(other.getHostAddresses());
+        mHostname = other.getHostname();
         mPort = other.getPort();
         mNetwork = other.getNetwork();
         mInterfaceIndex = other.getInterfaceIndex();
@@ -169,6 +175,43 @@
     }
 
     /**
+     * Get the hostname.
+     *
+     * <p>When a service is resolved, it returns the hostname of the resolved service . The top
+     * level domain ".local." is omitted.
+     *
+     * <p>For example, it returns "MyHost" when the service's hostname is "MyHost.local.".
+     *
+     * @hide
+     */
+//    @FlaggedApi(NsdManager.Flags.NSD_CUSTOM_HOSTNAME_ENABLED)
+    @Nullable
+    public String getHostname() {
+        return mHostname;
+    }
+
+    /**
+     * Set a custom hostname for this service instance for registration.
+     *
+     * <p>A hostname must be in ".local." domain. The ".local." must be omitted when calling this
+     * method.
+     *
+     * <p>For example, you should call setHostname("MyHost") to use the hostname "MyHost.local.".
+     *
+     * <p>If a hostname is set with this method, the addresses set with {@link #setHostAddresses}
+     * will be registered with the hostname.
+     *
+     * <p>If the hostname is null (which is the default for a new {@link NsdServiceInfo}), a random
+     * hostname is used and the addresses of this device will be registered.
+     *
+     * @hide
+     */
+//    @FlaggedApi(NsdManager.Flags.NSD_CUSTOM_HOSTNAME_ENABLED)
+    public void setHostname(@Nullable String hostname) {
+        mHostname = hostname;
+    }
+
+    /**
      * Unpack txt information from a base-64 encoded byte array.
      *
      * @param txtRecordsRawBytes The raw base64 encoded byte array.
@@ -454,6 +497,7 @@
                 .append(", type: ").append(mServiceType)
                 .append(", subtypes: ").append(TextUtils.join(", ", mSubtypes))
                 .append(", hostAddresses: ").append(TextUtils.join(", ", mHostAddresses))
+                .append(", hostname: ").append(mHostname)
                 .append(", port: ").append(mPort)
                 .append(", network: ").append(mNetwork);
 
@@ -494,6 +538,7 @@
         for (InetAddress address : mHostAddresses) {
             InetAddressUtils.parcelInetAddress(dest, address, flags);
         }
+        dest.writeString(mHostname);
     }
 
     /** Implement the Parcelable interface */
@@ -523,6 +568,7 @@
                 for (int i = 0; i < size; i++) {
                     info.mHostAddresses.add(InetAddressUtils.unparcelInetAddress(in));
                 }
+                info.mHostname = in.readString();
                 return info;
             }
 
diff --git a/service-t/src/com/android/server/NsdService.java b/service-t/src/com/android/server/NsdService.java
index be0b673..397e5a6 100644
--- a/service-t/src/com/android/server/NsdService.java
+++ b/service-t/src/com/android/server/NsdService.java
@@ -895,10 +895,18 @@
                                 serviceType);
                         final String registerServiceType = typeSubtype == null
                                 ? null : typeSubtype.first;
+                        final String hostname = serviceInfo.getHostname();
+                        // Keep compatible with the legacy behavior: It's allowed to set host
+                        // addresses for a service registration although the host addresses
+                        // won't be registered. To register the addresses for a host, the
+                        // hostname must be specified.
+                        if (hostname == null) {
+                            serviceInfo.setHostAddresses(Collections.emptyList());
+                        }
                         if (clientInfo.mUseJavaBackend
                                 || mDeps.isMdnsAdvertiserEnabled(mContext)
                                 || useAdvertiserForType(registerServiceType)) {
-                            if (registerServiceType == null) {
+                            if (serviceType != null && registerServiceType == null) {
                                 Log.e(TAG, "Invalid service type: " + serviceType);
                                 clientInfo.onRegisterServiceFailedImmediately(clientRequestId,
                                         NsdManager.FAILURE_INTERNAL_ERROR, false /* isLegacy */);
@@ -921,14 +929,25 @@
                             } else {
                                 transactionId = getUniqueId();
                             }
-                            serviceInfo.setServiceType(registerServiceType);
-                            serviceInfo.setServiceName(truncateServiceName(
-                                    serviceInfo.getServiceName()));
+
+                            if (registerServiceType != null) {
+                                serviceInfo.setServiceType(registerServiceType);
+                                serviceInfo.setServiceName(
+                                        truncateServiceName(serviceInfo.getServiceName()));
+                            }
+
+                            if (!checkHostname(hostname)) {
+                                clientInfo.onRegisterServiceFailedImmediately(clientRequestId,
+                                        NsdManager.FAILURE_BAD_PARAMETERS, false /* isLegacy */);
+                                break;
+                            }
 
                             Set<String> subtypes = new ArraySet<>(serviceInfo.getSubtypes());
-                            for (String subType: typeSubtype.second) {
-                                if (!TextUtils.isEmpty(subType)) {
-                                    subtypes.add(subType);
+                            if (typeSubtype != null && typeSubtype.second != null) {
+                                for (String subType : typeSubtype.second) {
+                                    if (!TextUtils.isEmpty(subType)) {
+                                        subtypes.add(subType);
+                                    }
                                 }
                             }
                             subtypes = dedupSubtypeLabels(subtypes);
@@ -945,7 +964,7 @@
                                     MdnsAdvertisingOptions.newBuilder().setIsOnlyUpdate(
                                             isUpdateOnly).build();
                             mAdvertiser.addOrUpdateService(transactionId, serviceInfo,
-                                    mdnsAdvertisingOptions);
+                                    mdnsAdvertisingOptions, clientInfo.mUid);
                             storeAdvertiserRequestMap(clientRequestId, transactionId, clientInfo,
                                     serviceInfo.getNetwork());
                         } else {
@@ -1535,6 +1554,7 @@
                                 Log.e(TAG, "Invalid attribute", e);
                             }
                         }
+                        info.setHostname(getHostname(serviceInfo));
                         final List<InetAddress> addresses = getInetAddresses(serviceInfo);
                         if (addresses.size() != 0) {
                             info.setHostAddresses(addresses);
@@ -1571,6 +1591,7 @@
                             }
                         }
 
+                        info.setHostname(getHostname(serviceInfo));
                         final List<InetAddress> addresses = getInetAddresses(serviceInfo);
                         info.setHostAddresses(addresses);
                         clientInfo.onServiceUpdated(clientRequestId, info, request);
@@ -1617,6 +1638,16 @@
         return addresses;
     }
 
+    @NonNull
+    private static String getHostname(@NonNull MdnsServiceInfo serviceInfo) {
+        String[] hostname = serviceInfo.getHostName();
+        // Strip the "local" top-level domain.
+        if (hostname.length >= 2 && hostname[hostname.length - 1].equals("local")) {
+            hostname = Arrays.copyOf(hostname, hostname.length - 1);
+        }
+        return String.join(".", hostname);
+    }
+
     private static void setServiceNetworkForCallback(NsdServiceInfo info, int netId, int ifaceIdx) {
         switch (netId) {
             case NETID_UNSET:
@@ -1702,6 +1733,21 @@
         return new Pair<>(queryType, Collections.emptyList());
     }
 
+    /**
+     * Checks if the hostname is valid.
+     *
+     * <p>For now NsdService only allows single-label hostnames conforming to RFC 1035. In other
+     * words, the hostname should be at most 63 characters long and it only contains letters, digits
+     * and hyphens.
+     */
+    public static boolean checkHostname(@Nullable String hostname) {
+        if (hostname == null) {
+            return true;
+        }
+        String HOSTNAME_REGEX = "^[a-zA-Z]([a-zA-Z0-9-_]{0,61}[a-zA-Z0-9])?$";
+        return Pattern.compile(HOSTNAME_REGEX).matcher(hostname).matches();
+    }
+
     /** Returns {@code true} if {@code subtype} is a valid DNS-SD subtype label. */
     private static boolean checkSubtypeLabel(String subtype) {
         return Pattern.compile("^" + TYPE_SUBTYPE_LABEL_REGEX + "$").matcher(subtype).matches();
@@ -2031,9 +2077,10 @@
             final int clientRequestId = getClientRequestIdOrLog(clientInfo, transactionId);
             if (clientRequestId < 0) return;
 
-            // onRegisterServiceSucceeded only has the service name in its info. This aligns with
-            // historical behavior.
+            // onRegisterServiceSucceeded only has the service name and hostname in its info. This
+            // aligns with historical behavior.
             final NsdServiceInfo cbInfo = new NsdServiceInfo(registeredInfo.getServiceName(), null);
+            cbInfo.setHostname(registeredInfo.getHostname());
             final ClientRequest request = clientInfo.mClientRequests.get(clientRequestId);
             clientInfo.onRegisterServiceSucceeded(clientRequestId, cbInfo, request);
         }
@@ -2143,6 +2190,7 @@
         @Override
         public void registerService(int listenerKey, AdvertisingRequest advertisingRequest)
                 throws RemoteException {
+            NsdManager.checkServiceInfoForRegistration(advertisingRequest.getServiceInfo());
             mNsdStateMachine.sendMessage(mNsdStateMachine.obtainMessage(
                     NsdManager.REGISTER_SERVICE, 0, listenerKey,
                     new AdvertisingArgs(this, advertisingRequest)
diff --git a/service-t/src/com/android/server/connectivity/mdns/MdnsAdvertiser.java b/service-t/src/com/android/server/connectivity/mdns/MdnsAdvertiser.java
index b2af93c..60859f8 100644
--- a/service-t/src/com/android/server/connectivity/mdns/MdnsAdvertiser.java
+++ b/service-t/src/com/android/server/connectivity/mdns/MdnsAdvertiser.java
@@ -17,6 +17,8 @@
 package com.android.server.connectivity.mdns;
 
 import static com.android.server.connectivity.mdns.MdnsConstants.NO_PACKET;
+import static com.android.server.connectivity.mdns.MdnsInterfaceAdvertiser.CONFLICT_HOST;
+import static com.android.server.connectivity.mdns.MdnsInterfaceAdvertiser.CONFLICT_SERVICE;
 import static com.android.server.connectivity.mdns.MdnsRecord.MAX_LABEL_LENGTH;
 
 import android.annotation.NonNull;
@@ -31,6 +33,7 @@
 import android.net.nsd.OffloadServiceInfo;
 import android.os.Build;
 import android.os.Looper;
+import android.text.TextUtils;
 import android.util.ArrayMap;
 import android.util.Log;
 import android.util.SparseArray;
@@ -151,7 +154,9 @@
                 mSharedLog.wtf("Register succeeded for unknown registration");
                 return;
             }
-            if (mMdnsFeatureFlags.mIsMdnsOffloadFeatureEnabled) {
+            if (mMdnsFeatureFlags.mIsMdnsOffloadFeatureEnabled
+                    // TODO: Enable offload when the serviceInfo contains a custom host.
+                    && TextUtils.isEmpty(registration.getServiceInfo().getHostname())) {
                 final String interfaceName = advertiser.getSocketInterfaceName();
                 final List<OffloadServiceInfoWrapper> existingOffloadServiceInfoWrappers =
                         mInterfaceOffloadServices.computeIfAbsent(interfaceName,
@@ -179,8 +184,11 @@
         }
 
         @Override
-        public void onServiceConflict(@NonNull MdnsInterfaceAdvertiser advertiser, int serviceId) {
-            mSharedLog.i("Found conflict, restarted probing for service " + serviceId);
+        public void onServiceConflict(@NonNull MdnsInterfaceAdvertiser advertiser, int serviceId,
+                int conflictType) {
+            mSharedLog.i("Found conflict, restarted probing for service "
+                    + serviceId + " "
+                    + conflictType);
 
             final Registration registration = mRegistrations.get(serviceId);
             if (registration == null) return;
@@ -205,10 +213,22 @@
                 return;
             }
 
-            // Conflict was found during probing; rename once to find a name that has no conflict
-            registration.updateForConflict(
-                    registration.makeNewServiceInfoForConflict(1 /* renameCount */),
-                    1 /* renameCount */);
+            if ((conflictType & CONFLICT_SERVICE) != 0) {
+                // Service conflict was found during probing; rename once to find a name that has no
+                // conflict
+                registration.updateForServiceConflict(
+                        registration.makeNewServiceInfoForServiceConflict(1 /* renameCount */),
+                        1 /* renameCount */);
+            }
+
+            if ((conflictType & CONFLICT_HOST) != 0) {
+                // Host conflict was found during probing; rename once to find a name that has no
+                // conflict
+                registration.updateForHostConflict(
+                        registration.makeNewServiceInfoForHostConflict(1 /* renameCount */),
+                        1 /* renameCount */);
+            }
+
             registration.mConflictDuringProbingCount++;
 
             // Keep renaming if the new name conflicts in local registrations
@@ -231,23 +251,53 @@
         }
     };
 
-    private boolean hasAnyConflict(
+    private boolean hasAnyServiceConflict(
             @NonNull BiPredicate<Network, InterfaceAdvertiserRequest> applicableAdvertiserFilter,
             @NonNull NsdServiceInfo newInfo) {
-        return any(mAdvertiserRequests, (network, adv) ->
-                applicableAdvertiserFilter.test(network, adv) && adv.hasConflict(newInfo));
+        return any(
+                mAdvertiserRequests,
+                (network, adv) ->
+                        applicableAdvertiserFilter.test(network, adv)
+                                && adv.hasServiceConflict(newInfo));
+    }
+
+    private boolean hasAnyHostConflict(
+            @NonNull BiPredicate<Network, InterfaceAdvertiserRequest> applicableAdvertiserFilter,
+            @NonNull NsdServiceInfo newInfo,
+            int clientUid) {
+        // Check if it conflicts with custom hosts.
+        if (any(
+                mAdvertiserRequests,
+                (network, adv) ->
+                        applicableAdvertiserFilter.test(network, adv)
+                                && adv.hasHostConflict(newInfo, clientUid))) {
+            return true;
+        }
+        // Check if it conflicts with the default hostname.
+        return MdnsUtils.equalsIgnoreDnsCase(newInfo.getHostname(), mDeviceHostName[0]);
     }
 
     private void updateRegistrationUntilNoConflict(
             @NonNull BiPredicate<Network, InterfaceAdvertiserRequest> applicableAdvertiserFilter,
             @NonNull Registration registration) {
-        int renameCount = 0;
         NsdServiceInfo newInfo = registration.getServiceInfo();
-        while (hasAnyConflict(applicableAdvertiserFilter, newInfo)) {
-            renameCount++;
-            newInfo = registration.makeNewServiceInfoForConflict(renameCount);
+
+        int renameServiceCount = 0;
+        while (hasAnyServiceConflict(applicableAdvertiserFilter, newInfo)) {
+            renameServiceCount++;
+            newInfo = registration.makeNewServiceInfoForServiceConflict(renameServiceCount);
         }
-        registration.updateForConflict(newInfo, renameCount);
+        registration.updateForServiceConflict(newInfo, renameServiceCount);
+
+        if (!TextUtils.isEmpty(registration.getServiceInfo().getHostname())) {
+            int renameHostCount = 0;
+            while (hasAnyHostConflict(
+                    applicableAdvertiserFilter, newInfo, registration.mClientUid)) {
+                renameHostCount++;
+                newInfo = registration.makeNewServiceInfoForHostConflict(renameHostCount);
+            }
+            registration.updateForHostConflict(newInfo, renameHostCount);
+        }
     }
 
     private void maybeSendOffloadStop(final String interfaceName, int serviceId) {
@@ -326,16 +376,27 @@
 
         /**
          * Return whether using the proposed new {@link NsdServiceInfo} to add a registration would
-         * cause a conflict in this {@link InterfaceAdvertiserRequest}.
+         * cause a conflict of the service in this {@link InterfaceAdvertiserRequest}.
          */
-        boolean hasConflict(@NonNull NsdServiceInfo newInfo) {
-            return getConflictingService(newInfo) >= 0;
+        boolean hasServiceConflict(@NonNull NsdServiceInfo newInfo) {
+            return getConflictingRegistrationDueToService(newInfo) >= 0;
         }
 
         /**
-         * Get the ID of a conflicting service, or -1 if none.
+         * Return whether using the proposed new {@link NsdServiceInfo} to add a registration would
+         * cause a conflict of the host in this {@link InterfaceAdvertiserRequest}.
+         *
+         * @param clientUid UID of the user who wants to advertise the serviceInfo.
          */
-        int getConflictingService(@NonNull NsdServiceInfo info) {
+        boolean hasHostConflict(@NonNull NsdServiceInfo newInfo, int clientUid) {
+            return getConflictingRegistrationDueToHost(newInfo, clientUid) >= 0;
+        }
+
+        /** Get the ID of a conflicting registration due to service, or -1 if none. */
+        int getConflictingRegistrationDueToService(@NonNull NsdServiceInfo info) {
+            if (TextUtils.isEmpty(info.getServiceName())) {
+                return -1;
+            }
             for (int i = 0; i < mPendingRegistrations.size(); i++) {
                 final NsdServiceInfo other = mPendingRegistrations.valueAt(i).getServiceInfo();
                 if (MdnsUtils.equalsIgnoreDnsCase(info.getServiceName(), other.getServiceName())
@@ -348,9 +409,34 @@
         }
 
         /**
+         * Get the ID of a conflicting registration due to host, or -1 if none.
+         *
+         * <p>It's valid that multiple registrations from the same user are using the same hostname.
+         *
+         * <p>If there's already another registration with the same hostname requested by another
+         * user, this is considered a conflict.
+         */
+        int getConflictingRegistrationDueToHost(@NonNull NsdServiceInfo info, int clientUid) {
+            if (TextUtils.isEmpty(info.getHostname())) {
+                return -1;
+            }
+            for (int i = 0; i < mPendingRegistrations.size(); i++) {
+                final Registration otherRegistration = mPendingRegistrations.valueAt(i);
+                final NsdServiceInfo otherInfo = otherRegistration.getServiceInfo();
+                if (clientUid != otherRegistration.mClientUid
+                        && MdnsUtils.equalsIgnoreDnsCase(
+                                info.getHostname(), otherInfo.getHostname())) {
+                    return mPendingRegistrations.keyAt(i);
+                }
+            }
+            return -1;
+        }
+
+        /**
          * Add a service to advertise.
          *
-         * Conflicts must be checked via {@link #getConflictingService} before attempting to add.
+         * <p>Conflicts must be checked via {@link #getConflictingRegistrationDueToService} and
+         * {@link #getConflictingRegistrationDueToHost} before attempting to add.
          */
         void addService(int id, @NonNull Registration registration) {
             mPendingRegistrations.put(id, registration);
@@ -484,27 +570,35 @@
     }
 
     private static class Registration {
-        @NonNull
-        final String mOriginalName;
+        @Nullable
+        final String mOriginalServiceName;
+        @Nullable
+        final String mOriginalHostname;
         boolean mNotifiedRegistrationSuccess;
-        private int mConflictCount;
+        private int mServiceNameConflictCount;
+        private int mHostnameConflictCount;
         @NonNull
         private NsdServiceInfo mServiceInfo;
+        final int mClientUid;
         int mConflictDuringProbingCount;
         int mConflictAfterProbingCount;
 
-        private Registration(@NonNull NsdServiceInfo serviceInfo) {
-            this.mOriginalName = serviceInfo.getServiceName();
+
+        private Registration(@NonNull NsdServiceInfo serviceInfo, int clientUid) {
+            this.mOriginalServiceName = serviceInfo.getServiceName();
+            this.mOriginalHostname = serviceInfo.getHostname();
             this.mServiceInfo = serviceInfo;
+            this.mClientUid = clientUid;
         }
 
-        /**
-         * Matches between the NsdServiceInfo in the Registration and the provided argument.
-         */
-        public boolean matches(@Nullable NsdServiceInfo newInfo) {
-            return Objects.equals(newInfo.getServiceName(), mOriginalName) && Objects.equals(
-                    newInfo.getServiceType(), mServiceInfo.getServiceType()) && Objects.equals(
-                    newInfo.getNetwork(), mServiceInfo.getNetwork());
+        /** Check if the new {@link NsdServiceInfo} doesn't update any data other than subtypes. */
+        public boolean isSubtypeOnlyUpdate(@NonNull NsdServiceInfo newInfo) {
+            return Objects.equals(newInfo.getServiceName(), mOriginalServiceName)
+                    && Objects.equals(newInfo.getServiceType(), mServiceInfo.getServiceType())
+                    && newInfo.getPort() == mServiceInfo.getPort()
+                    && Objects.equals(newInfo.getHostname(), mOriginalHostname)
+                    && Objects.equals(newInfo.getHostAddresses(), mServiceInfo.getHostAddresses())
+                    && Objects.equals(newInfo.getNetwork(), mServiceInfo.getNetwork());
         }
 
         /**
@@ -521,8 +615,19 @@
          * @param newInfo New service info to use.
          * @param renameCount How many renames were done before reaching the current name.
          */
-        private void updateForConflict(@NonNull NsdServiceInfo newInfo, int renameCount) {
-            mConflictCount += renameCount;
+        private void updateForServiceConflict(@NonNull NsdServiceInfo newInfo, int renameCount) {
+            mServiceNameConflictCount += renameCount;
+            mServiceInfo = newInfo;
+        }
+
+        /**
+         * Update the registration to use a different host name, after a conflict was found.
+         *
+         * @param newInfo New service info to use.
+         * @param renameCount How many renames were done before reaching the current name.
+         */
+        private void updateForHostConflict(@NonNull NsdServiceInfo newInfo, int renameCount) {
+            mHostnameConflictCount += renameCount;
             mServiceInfo = newInfo;
         }
 
@@ -538,7 +643,7 @@
          * @param renameCount How much to increase the number suffix for this conflict.
          */
         @NonNull
-        public NsdServiceInfo makeNewServiceInfoForConflict(int renameCount) {
+        public NsdServiceInfo makeNewServiceInfoForServiceConflict(int renameCount) {
             // In case of conflict choose a different service name. After the first conflict use
             // "Name (2)", then "Name (3)" etc.
             // TODO: use a hidden method in NsdServiceInfo once MdnsAdvertiser is moved to service-t
@@ -547,13 +652,40 @@
             return newInfo;
         }
 
+        /**
+         * Make a new hostname for the registration, after a conflict was found.
+         *
+         * <p>If a name conflict was found during probing or because different advertising requests
+         * used the same name, the registration is attempted again with a new name (here using a
+         * number suffix, -1, -2, etc). Registration success is notified once probing succeeds with
+         * a new name.
+         *
+         * @param renameCount How much to increase the number suffix for this conflict.
+         */
+        @NonNull
+        public NsdServiceInfo makeNewServiceInfoForHostConflict(int renameCount) {
+            // In case of conflict choose a different hostname. After the first conflict use
+            // "Name-2", then "Name-3" etc.
+            final NsdServiceInfo newInfo = new NsdServiceInfo(mServiceInfo);
+            newInfo.setHostname(getUpdatedHostname(renameCount));
+            return newInfo;
+        }
+
         private String getUpdatedServiceName(int renameCount) {
-            final String suffix = " (" + (mConflictCount + renameCount + 1) + ")";
-            final String truncatedServiceName = MdnsUtils.truncateServiceName(mOriginalName,
+            final String suffix = " (" + (mServiceNameConflictCount + renameCount + 1) + ")";
+            final String truncatedServiceName = MdnsUtils.truncateServiceName(mOriginalServiceName,
                     MAX_LABEL_LENGTH - suffix.length());
             return truncatedServiceName + suffix;
         }
 
+        private String getUpdatedHostname(int renameCount) {
+            final String suffix = "-" + (mHostnameConflictCount + renameCount + 1);
+            final String truncatedHostname =
+                    MdnsUtils.truncateServiceName(
+                            mOriginalHostname, MAX_LABEL_LENGTH - suffix.length());
+            return truncatedHostname + suffix;
+        }
+
         @NonNull
         public NsdServiceInfo getServiceInfo() {
             return mServiceInfo;
@@ -681,9 +813,10 @@
      * @param id A unique ID for the service.
      * @param service The service info to advertise.
      * @param advertisingOptions The advertising options.
+     * @param clientUid The UID who wants to advertise the service.
      */
     public void addOrUpdateService(int id, NsdServiceInfo service,
-            MdnsAdvertisingOptions advertisingOptions) {
+            MdnsAdvertisingOptions advertisingOptions, int clientUid) {
         checkThread();
         final Registration existingRegistration = mRegistrations.get(id);
         final Network network = service.getNetwork();
@@ -695,7 +828,7 @@
                 mCb.onRegisterServiceFailed(id, NsdManager.FAILURE_INTERNAL_ERROR);
                 return;
             }
-            if (!(existingRegistration.matches(service))) {
+            if (!(existingRegistration.isSubtypeOnlyUpdate(service))) {
                 mSharedLog.e("Update request can only update subType, serviceInfo: " + service
                         + ", existing serviceInfo: " + existingRegistration.getServiceInfo());
                 mCb.onRegisterServiceFailed(id, NsdManager.FAILURE_INTERNAL_ERROR);
@@ -715,7 +848,7 @@
             }
             mSharedLog.i("Adding service " + service + " with ID " + id + " and subtypes "
                     + subtypes + " advertisingOptions " + advertisingOptions);
-            registration = new Registration(service);
+            registration = new Registration(service, clientUid);
             final BiPredicate<Network, InterfaceAdvertiserRequest> checkConflictFilter;
             if (network == null) {
                 // If registering on all networks, no advertiser must have conflicts
diff --git a/service-t/src/com/android/server/connectivity/mdns/MdnsInterfaceAdvertiser.java b/service-t/src/com/android/server/connectivity/mdns/MdnsInterfaceAdvertiser.java
index 730bd7e..f1deab0 100644
--- a/service-t/src/com/android/server/connectivity/mdns/MdnsInterfaceAdvertiser.java
+++ b/service-t/src/com/android/server/connectivity/mdns/MdnsInterfaceAdvertiser.java
@@ -22,10 +22,12 @@
 import android.annotation.Nullable;
 import android.annotation.RequiresApi;
 import android.net.LinkAddress;
+import android.net.nsd.NsdManager;
 import android.net.nsd.NsdServiceInfo;
 import android.os.Build;
 import android.os.Handler;
 import android.os.Looper;
+import android.util.ArraySet;
 
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.net.module.util.HexDump;
@@ -37,6 +39,7 @@
 import java.io.IOException;
 import java.net.InetSocketAddress;
 import java.util.List;
+import java.util.Map;
 import java.util.Set;
 
 /**
@@ -44,6 +47,9 @@
  */
 @RequiresApi(Build.VERSION_CODES.TIRAMISU)
 public class MdnsInterfaceAdvertiser implements MulticastPacketReader.PacketHandler {
+    public static final int CONFLICT_SERVICE = 1 << 0;
+    public static final int CONFLICT_HOST = 1 << 1;
+
     private static final boolean DBG = MdnsAdvertiser.DBG;
     @VisibleForTesting
     public static final long EXIT_ANNOUNCEMENT_DELAY_MS = 100L;
@@ -85,10 +91,15 @@
         /**
          * Called by the advertiser when a conflict was found, during or after probing.
          *
-         * If a conflict is found during probing, the {@link #renameServiceForConflict} must be
+         * <p>If a conflict is found during probing, the {@link #renameServiceForConflict} must be
          * called to restart probing and attempt registration with a different name.
+         *
+         * <p>{@code conflictType} is a bitmap telling which part of the service is conflicting. See
+         * {@link MdnsInterfaceAdvertiser#CONFLICT_SERVICE} and {@link
+         * MdnsInterfaceAdvertiser#CONFLICT_HOST}.
          */
-        void onServiceConflict(@NonNull MdnsInterfaceAdvertiser advertiser, int serviceId);
+        void onServiceConflict(
+                @NonNull MdnsInterfaceAdvertiser advertiser, int serviceId, int conflictType);
 
         /**
          * Called by the advertiser when it destroyed itself.
@@ -384,8 +395,16 @@
                     + packet.additionalRecords.size() + " additional from " + srcCopy);
         }
 
-        for (int conflictServiceId : mRecordRepository.getConflictingServices(packet)) {
-            mCbHandler.post(() -> mCb.onServiceConflict(this, conflictServiceId));
+        Map<Integer, Integer> conflictingServices =
+                mRecordRepository.getConflictingServices(packet);
+
+        for (Map.Entry<Integer, Integer> entry : conflictingServices.entrySet()) {
+            int serviceId = entry.getKey();
+            int conflictType = entry.getValue();
+            mCbHandler.post(
+                    () -> {
+                        mCb.onServiceConflict(this, serviceId, conflictType);
+                    });
         }
 
         // Even in case of conflict, add replies for other services. But in general conflicts would
diff --git a/service-t/src/com/android/server/connectivity/mdns/MdnsRecordRepository.java b/service-t/src/com/android/server/connectivity/mdns/MdnsRecordRepository.java
index 78c3082..fb45454 100644
--- a/service-t/src/com/android/server/connectivity/mdns/MdnsRecordRepository.java
+++ b/service-t/src/com/android/server/connectivity/mdns/MdnsRecordRepository.java
@@ -19,6 +19,8 @@
 import static com.android.server.connectivity.mdns.MdnsConstants.IPV4_SOCKET_ADDR;
 import static com.android.server.connectivity.mdns.MdnsConstants.IPV6_SOCKET_ADDR;
 import static com.android.server.connectivity.mdns.MdnsConstants.NO_PACKET;
+import static com.android.server.connectivity.mdns.MdnsInterfaceAdvertiser.CONFLICT_HOST;
+import static com.android.server.connectivity.mdns.MdnsInterfaceAdvertiser.CONFLICT_SERVICE;
 
 import android.annotation.NonNull;
 import android.annotation.Nullable;
@@ -28,6 +30,8 @@
 import android.os.Build;
 import android.os.Looper;
 import android.os.SystemClock;
+import android.text.TextUtils;
+import android.util.ArrayMap;
 import android.util.ArraySet;
 import android.util.SparseArray;
 
@@ -54,6 +58,8 @@
 import java.util.Set;
 import java.util.TreeMap;
 import java.util.concurrent.TimeUnit;
+import java.util.function.BiConsumer;
+import java.util.function.Consumer;
 
 /**
  * A repository of records advertised through {@link MdnsInterfaceAdvertiser}.
@@ -158,11 +164,13 @@
         public final List<RecordInfo<?>> allRecords;
         @NonNull
         public final List<RecordInfo<MdnsPointerRecord>> ptrRecords;
-        @NonNull
+        @Nullable
         public final RecordInfo<MdnsServiceRecord> srvRecord;
-        @NonNull
+        @Nullable
         public final RecordInfo<MdnsTextRecord> txtRecord;
         @NonNull
+        public final List<RecordInfo<MdnsInetAddressRecord>> addressRecords;
+        @NonNull
         public final NsdServiceInfo serviceInfo;
 
         /**
@@ -202,65 +210,96 @@
                 int repliedServiceCount, int sentPacketCount, boolean exiting, boolean isProbing) {
             this.serviceInfo = serviceInfo;
 
-            final String[] serviceType = splitServiceType(serviceInfo);
-            final String[] serviceName = splitFullyQualifiedName(serviceInfo, serviceType);
+            final boolean hasService = !TextUtils.isEmpty(serviceInfo.getServiceType());
+            final boolean hasCustomHost = !TextUtils.isEmpty(serviceInfo.getHostname());
+            final String[] hostname =
+                    hasCustomHost
+                            ? new String[] {serviceInfo.getHostname(), LOCAL_TLD}
+                            : deviceHostname;
+            final ArrayList<RecordInfo<?>> allRecords = new ArrayList<>(5);
 
-            // Service PTR records
-            ptrRecords = new ArrayList<>(serviceInfo.getSubtypes().size() + 1);
-            ptrRecords.add(new RecordInfo<>(
-                    serviceInfo,
-                    new MdnsPointerRecord(
-                            serviceType,
-                            0L /* receiptTimeMillis */,
-                            false /* cacheFlush */,
-                            NON_NAME_RECORDS_TTL_MILLIS,
-                            serviceName),
-                    true /* sharedName */));
-            for (String subtype : serviceInfo.getSubtypes()) {
+            if (hasService) {
+                final String[] serviceType = splitServiceType(serviceInfo);
+                final String[] serviceName = splitFullyQualifiedName(serviceInfo, serviceType);
+                // Service PTR records
+                ptrRecords = new ArrayList<>(serviceInfo.getSubtypes().size() + 1);
                 ptrRecords.add(new RecordInfo<>(
-                    serviceInfo,
-                    new MdnsPointerRecord(
-                            MdnsUtils.constructFullSubtype(serviceType, subtype),
-                            0L /* receiptTimeMillis */,
-                            false /* cacheFlush */,
-                            NON_NAME_RECORDS_TTL_MILLIS,
-                            serviceName),
-                    true /* sharedName */));
+                        serviceInfo,
+                        new MdnsPointerRecord(
+                                serviceType,
+                                0L /* receiptTimeMillis */,
+                                false /* cacheFlush */,
+                                NON_NAME_RECORDS_TTL_MILLIS,
+                                serviceName),
+                        true /* sharedName */));
+                for (String subtype : serviceInfo.getSubtypes()) {
+                    ptrRecords.add(new RecordInfo<>(
+                            serviceInfo,
+                            new MdnsPointerRecord(
+                                    MdnsUtils.constructFullSubtype(serviceType, subtype),
+                                    0L /* receiptTimeMillis */,
+                                    false /* cacheFlush */,
+                                    NON_NAME_RECORDS_TTL_MILLIS,
+                                    serviceName),
+                            true /* sharedName */));
+                }
+
+                srvRecord = new RecordInfo<>(
+                        serviceInfo,
+                        new MdnsServiceRecord(serviceName,
+                                0L /* receiptTimeMillis */,
+                                true /* cacheFlush */,
+                                NAME_RECORDS_TTL_MILLIS,
+                                0 /* servicePriority */, 0 /* serviceWeight */,
+                                serviceInfo.getPort(),
+                                hostname),
+                        false /* sharedName */);
+
+                txtRecord = new RecordInfo<>(
+                        serviceInfo,
+                        new MdnsTextRecord(serviceName,
+                                0L /* receiptTimeMillis */,
+                                // Service name is verified unique after probing
+                                true /* cacheFlush */,
+                                NON_NAME_RECORDS_TTL_MILLIS,
+                                attrsToTextEntries(serviceInfo.getAttributes())),
+                        false /* sharedName */);
+
+                allRecords.addAll(ptrRecords);
+                allRecords.add(srvRecord);
+                allRecords.add(txtRecord);
+                // Service type enumeration record (RFC6763 9.)
+                allRecords.add(new RecordInfo<>(
+                        serviceInfo,
+                        new MdnsPointerRecord(
+                                DNS_SD_SERVICE_TYPE,
+                                0L /* receiptTimeMillis */,
+                                false /* cacheFlush */,
+                                NON_NAME_RECORDS_TTL_MILLIS,
+                                serviceType),
+                        true /* sharedName */));
+            } else {
+                ptrRecords = Collections.emptyList();
+                srvRecord = null;
+                txtRecord = null;
             }
 
-            srvRecord = new RecordInfo<>(
-                    serviceInfo,
-                    new MdnsServiceRecord(serviceName,
-                            0L /* receiptTimeMillis */,
-                            true /* cacheFlush */,
-                            NAME_RECORDS_TTL_MILLIS, 0 /* servicePriority */, 0 /* serviceWeight */,
-                            serviceInfo.getPort(),
-                            deviceHostname),
-                    false /* sharedName */);
-
-            txtRecord = new RecordInfo<>(
-                    serviceInfo,
-                    new MdnsTextRecord(serviceName,
-                            0L /* receiptTimeMillis */,
-                            true /* cacheFlush */, // Service name is verified unique after probing
-                            NON_NAME_RECORDS_TTL_MILLIS,
-                            attrsToTextEntries(serviceInfo.getAttributes())),
-                    false /* sharedName */);
-
-            final ArrayList<RecordInfo<?>> allRecords = new ArrayList<>(5);
-            allRecords.addAll(ptrRecords);
-            allRecords.add(srvRecord);
-            allRecords.add(txtRecord);
-            // Service type enumeration record (RFC6763 9.)
-            allRecords.add(new RecordInfo<>(
-                    serviceInfo,
-                    new MdnsPointerRecord(
-                            DNS_SD_SERVICE_TYPE,
-                            0L /* receiptTimeMillis */,
-                            false /* cacheFlush */,
-                            NON_NAME_RECORDS_TTL_MILLIS,
-                            serviceType),
-                    true /* sharedName */));
+            if (hasCustomHost) {
+                addressRecords = new ArrayList<>(serviceInfo.getHostAddresses().size());
+                for (InetAddress address : serviceInfo.getHostAddresses()) {
+                    addressRecords.add(new RecordInfo<>(
+                                    serviceInfo,
+                                    new MdnsInetAddressRecord(hostname,
+                                            0L /* receiptTimeMillis */,
+                                            true /* cacheFlush */,
+                                            NAME_RECORDS_TTL_MILLIS,
+                                            address),
+                                    false /* sharedName */));
+                }
+                allRecords.addAll(addressRecords);
+            } else {
+                addressRecords = Collections.emptyList();
+            }
 
             this.allRecords = Collections.unmodifiableList(allRecords);
             this.repliedServiceCount = repliedServiceCount;
@@ -368,32 +407,38 @@
     /**
      * @return The ID of the service identified by its name, or -1 if none.
      */
-    private int getServiceByName(@NonNull String serviceName) {
+    private int getServiceByName(@Nullable String serviceName) {
+        if (TextUtils.isEmpty(serviceName)) {
+            return -1;
+        }
         for (int i = 0; i < mServices.size(); i++) {
             final ServiceRegistration registration = mServices.valueAt(i);
-            if (MdnsUtils.equalsIgnoreDnsCase(serviceName,
-                    registration.serviceInfo.getServiceName())) {
+            if (MdnsUtils.equalsIgnoreDnsCase(
+                    serviceName, registration.serviceInfo.getServiceName())) {
                 return mServices.keyAt(i);
             }
         }
         return -1;
     }
 
-    private MdnsProber.ProbingInfo makeProbingInfo(int serviceId,
-            @NonNull MdnsServiceRecord srvRecord,
-            @NonNull List<MdnsInetAddressRecord> inetAddressRecords) {
+    private MdnsProber.ProbingInfo makeProbingInfo(
+            int serviceId, ServiceRegistration registration) {
         final List<MdnsRecord> probingRecords = new ArrayList<>();
         // Probe with cacheFlush cleared; it is set when announcing, as it was verified unique:
         // RFC6762 10.2
-        probingRecords.add(new MdnsServiceRecord(srvRecord.getName(),
-                0L /* receiptTimeMillis */,
-                false /* cacheFlush */,
-                srvRecord.getTtl(),
-                srvRecord.getServicePriority(), srvRecord.getServiceWeight(),
-                srvRecord.getServicePort(),
-                srvRecord.getServiceHost()));
+        if (registration.srvRecord != null) {
+            MdnsServiceRecord srvRecord = registration.srvRecord.record;
+            probingRecords.add(new MdnsServiceRecord(srvRecord.getName(),
+                    0L /* receiptTimeMillis */,
+                    false /* cacheFlush */,
+                    srvRecord.getTtl(),
+                    srvRecord.getServicePriority(), srvRecord.getServiceWeight(),
+                    srvRecord.getServicePort(),
+                    srvRecord.getServiceHost()));
+        }
 
-        for (MdnsInetAddressRecord inetAddressRecord : inetAddressRecords) {
+        for (MdnsInetAddressRecord inetAddressRecord :
+                makeProbingInetAddressRecords(registration.serviceInfo)) {
             probingRecords.add(new MdnsInetAddressRecord(inetAddressRecord.getName(),
                     0L /* receiptTimeMillis */,
                     false /* cacheFlush */,
@@ -510,6 +555,9 @@
     public MdnsReplyInfo getReply(MdnsPacket packet, InetSocketAddress src) {
         final long now = SystemClock.elapsedRealtime();
 
+        // TODO: b/322142420 - Set<RecordInfo<?>> may contain duplicate records wrapped in different
+        // RecordInfo<?>s when custom host is enabled.
+
         // Use LinkedHashSet for preserving the insert order of the RRs, so that RRs of the same
         // service or host are grouped together (which is more developer-friendly).
         final Set<RecordInfo<?>> answerInfo = new LinkedHashSet<>();
@@ -520,8 +568,10 @@
         for (MdnsRecord question : packet.questions) {
             // Add answers from general records
             if (addReplyFromService(question, mGeneralRecords, null /* servicePtrRecord */,
-                    null /* serviceSrvRecord */, null /* serviceTxtRecord */, replyUnicastEnabled,
-                    now, answerInfo, additionalAnswerInfo, Collections.emptyList())) {
+                    null /* serviceSrvRecord */, null /* serviceTxtRecord */,
+                    null /* hostname */,
+                    replyUnicastEnabled, now, answerInfo, additionalAnswerInfo,
+                    Collections.emptyList())) {
                 replyUnicast &= question.isUnicastReplyRequested();
             }
 
@@ -530,7 +580,9 @@
                 final ServiceRegistration registration = mServices.valueAt(i);
                 if (registration.exiting || registration.isProbing) continue;
                 if (addReplyFromService(question, registration.allRecords, registration.ptrRecords,
-                        registration.srvRecord, registration.txtRecord, replyUnicastEnabled, now,
+                        registration.srvRecord, registration.txtRecord,
+                        registration.serviceInfo.getHostname(),
+                        replyUnicastEnabled, now,
                         answerInfo, additionalAnswerInfo, packet.answers)) {
                     replyUnicast &= question.isUnicastReplyRequested();
                     registration.repliedServiceCount++;
@@ -548,7 +600,12 @@
         final List<MdnsRecord> additionalAnswerRecords =
                 new ArrayList<>(additionalAnswerInfo.size());
         for (RecordInfo<?> info : additionalAnswerInfo) {
-            additionalAnswerRecords.add(info.record);
+            // Different RecordInfos may contain the same record.
+            // For example, when there are multiple services referring to the same custom host,
+            // there are multiple RecordInfos containing the same address record.
+            if (!additionalAnswerRecords.contains(info.record)) {
+                additionalAnswerRecords.add(info.record);
+            }
         }
 
         // RFC6762 6.1: negative responses
@@ -618,7 +675,10 @@
             if (!replyUnicast) {
                 info.lastAdvertisedTimeMs = info.lastSentTimeMs;
             }
-            answerRecords.add(info.record);
+            // Different RecordInfos may the contain the same record
+            if (!answerRecords.contains(info.record)) {
+                answerRecords.add(info.record);
+            }
         }
 
         return new MdnsReplyInfo(answerRecords, additionalAnswerRecords, delayMs, dest, src,
@@ -642,6 +702,7 @@
             @Nullable List<RecordInfo<MdnsPointerRecord>> servicePtrRecords,
             @Nullable RecordInfo<MdnsServiceRecord> serviceSrvRecord,
             @Nullable RecordInfo<MdnsTextRecord> serviceTxtRecord,
+            @Nullable String hostname,
             boolean replyUnicastEnabled, long now, @NonNull Set<RecordInfo<?>> answerInfo,
             @NonNull Set<RecordInfo<?>> additionalAnswerInfo,
             @NonNull List<MdnsRecord> knownAnswerRecords) {
@@ -735,11 +796,7 @@
 
         // RFC6763 12.1&.2: if including PTR or SRV record, include the address records it names
         if (hasDnsSdPtrRecordAnswer || hasDnsSdSrvRecordAnswer) {
-            for (RecordInfo<?> record : mGeneralRecords) {
-                if (record.record instanceof MdnsInetAddressRecord) {
-                    additionalAnswerInfo.add(record);
-                }
-            }
+            additionalAnswerInfo.addAll(getInetAddressRecordsForHostname(hostname));
         }
         return true;
     }
@@ -853,29 +910,46 @@
             MdnsProber.ProbingInfo probeSuccessInfo)
             throws IOException {
 
-        final ServiceRegistration registration = mServices.get(probeSuccessInfo.getServiceId());
-        if (registration == null) throw new IOException(
-                "Service is not registered: " + probeSuccessInfo.getServiceId());
+        int serviceId = probeSuccessInfo.getServiceId();
+        final ServiceRegistration registration = mServices.get(serviceId);
+        if (registration == null) {
+            throw new IOException("Service is not registered: " + serviceId);
+        }
         registration.setProbing(false);
 
-        final ArrayList<MdnsRecord> answers = new ArrayList<>();
+        final Set<MdnsRecord> answersSet = new LinkedHashSet<>();
         final ArrayList<MdnsRecord> additionalAnswers = new ArrayList<>();
 
-        // Interface address records in general records
-        for (RecordInfo<?> record : mGeneralRecords) {
-            answers.add(record.record);
+        // When using default host, add interface address records from general records
+        if (TextUtils.isEmpty(registration.serviceInfo.getHostname())) {
+            for (RecordInfo<?> record : mGeneralRecords) {
+                answersSet.add(record.record);
+            }
+        } else {
+            // TODO: b/321617573 - include PTR records for addresses
+            // The custom host may have more addresses in other registrations
+            forEachActiveServiceRegistrationWithHostname(
+                    registration.serviceInfo.getHostname(),
+                    (id, otherRegistration) -> {
+                        if (otherRegistration.isProbing) {
+                            return;
+                        }
+                        for (RecordInfo<?> addressRecordInfo : otherRegistration.addressRecords) {
+                            answersSet.add(addressRecordInfo.record);
+                        }
+                    });
         }
 
         // All service records
         for (RecordInfo<?> info : registration.allRecords) {
-            answers.add(info.record);
+            answersSet.add(info.record);
         }
 
         addNsecRecordsForUniqueNames(additionalAnswers,
                 mGeneralRecords.iterator(), registration.allRecords.iterator());
 
-        return new MdnsAnnouncer.AnnouncementInfo(probeSuccessInfo.getServiceId(),
-                answers, additionalAnswers);
+        return new MdnsAnnouncer.AnnouncementInfo(
+                probeSuccessInfo.getServiceId(), new ArrayList<>(answersSet), additionalAnswers);
     }
 
     /**
@@ -894,8 +968,13 @@
         for (RecordInfo<MdnsPointerRecord> ptrRecord : registration.ptrRecords) {
             answers.add(ptrRecord.record);
         }
-        answers.add(registration.srvRecord.record);
-        answers.add(registration.txtRecord.record);
+        if (registration.srvRecord != null) {
+            answers.add(registration.srvRecord.record);
+        }
+        if (registration.txtRecord != null) {
+            answers.add(registration.txtRecord.record);
+        }
+        // TODO: Support custom host. It currently only supports default host.
         for (RecordInfo<?> record : mGeneralRecords) {
             if (record.record instanceof MdnsInetAddressRecord) {
                 answers.add(record.record);
@@ -910,70 +989,181 @@
                 Collections.emptyList() /* additionalRecords */);
     }
 
+    /** Check if the record is in any service registration */
+    private boolean hasInetAddressRecord(@NonNull MdnsInetAddressRecord record) {
+        for (int i = 0; i < mServices.size(); i++) {
+            final ServiceRegistration registration = mServices.valueAt(i);
+            if (registration.exiting) continue;
+
+            for (RecordInfo<MdnsInetAddressRecord> localRecord : registration.addressRecords) {
+                if (Objects.equals(localRecord.record, record)) {
+                    return true;
+                }
+            }
+        }
+        return false;
+    }
+
     /**
      * Get the service IDs of services conflicting with a received packet.
+     *
+     * <p>It returns a Map of service ID => conflict type. Conflict type is a bitmap telling which
+     * part of the service is conflicting. See {@link MdnsInterfaceAdvertiser#CONFLICT_SERVICE} and
+     * {@link MdnsInterfaceAdvertiser#CONFLICT_HOST}.
      */
-    public Set<Integer> getConflictingServices(MdnsPacket packet) {
+    public Map<Integer, Integer> getConflictingServices(MdnsPacket packet) {
         // Avoid allocating a new set for each incoming packet: use an empty set by default.
-        Set<Integer> conflicting = Collections.emptySet();
+        Map<Integer, Integer> conflicting = Collections.emptyMap();
         for (MdnsRecord record : packet.answers) {
             for (int i = 0; i < mServices.size(); i++) {
                 final ServiceRegistration registration = mServices.valueAt(i);
                 if (registration.exiting) continue;
 
-                // Only look for conflicts in service name, as a different service name can be used
-                // if there is a conflict, but there is nothing actionable if any other conflict
-                // happens. In fact probing is only done for the service name in the SRV record.
-                // This means only SRV and TXT records need to be checked.
-                final RecordInfo<MdnsServiceRecord> srvRecord = registration.srvRecord;
-                if (!MdnsUtils.equalsDnsLabelIgnoreDnsCase(record.getName(),
-                        srvRecord.record.getName())) {
-                    continue;
+                int conflictType = 0;
+
+                if (conflictForService(record, registration)) {
+                    conflictType |= CONFLICT_SERVICE;
                 }
 
-                // As per RFC6762 9., it's fine if the "conflict" is an identical record with same
-                // data.
-                if (record instanceof MdnsServiceRecord) {
-                    final MdnsServiceRecord local = srvRecord.record;
-                    final MdnsServiceRecord other = (MdnsServiceRecord) record;
-                    // Note "equals" does not consider TTL or receipt time, as intended here
-                    if (Objects.equals(local, other)) {
-                        continue;
+                if (conflictForHost(record, registration)) {
+                    conflictType |= CONFLICT_HOST;
+                }
+
+                if (conflictType != 0) {
+                    if (conflicting.isEmpty()) {
+                        // Conflict was found: use a mutable set
+                        conflicting = new ArrayMap<>();
                     }
+                    final int serviceId = mServices.keyAt(i);
+                    conflicting.put(serviceId, conflictType);
                 }
-
-                if (record instanceof MdnsTextRecord) {
-                    final MdnsTextRecord local = registration.txtRecord.record;
-                    final MdnsTextRecord other = (MdnsTextRecord) record;
-                    if (Objects.equals(local, other)) {
-                        continue;
-                    }
-                }
-
-                if (conflicting.size() == 0) {
-                    // Conflict was found: use a mutable set
-                    conflicting = new ArraySet<>();
-                }
-                final int serviceId = mServices.keyAt(i);
-                conflicting.add(serviceId);
             }
         }
 
         return conflicting;
     }
 
-    private List<MdnsInetAddressRecord> makeProbingInetAddressRecords() {
-        final List<MdnsInetAddressRecord> records = new ArrayList<>();
-        if (mMdnsFeatureFlags.mIncludeInetAddressRecordsInProbing) {
-            for (RecordInfo<?> record : mGeneralRecords) {
-                if (record.record instanceof MdnsInetAddressRecord) {
-                    records.add((MdnsInetAddressRecord) record.record);
-                }
+
+    private static boolean conflictForService(
+            @NonNull MdnsRecord record, @NonNull ServiceRegistration registration) {
+        if (registration.srvRecord == null) {
+            return false;
+        }
+
+        final RecordInfo<MdnsServiceRecord> srvRecord = registration.srvRecord;
+        if (!MdnsUtils.equalsDnsLabelIgnoreDnsCase(record.getName(), srvRecord.record.getName())) {
+            return false;
+        }
+
+        // As per RFC6762 9., it's fine if the "conflict" is an identical record with same
+        // data.
+        if (record instanceof MdnsServiceRecord) {
+            final MdnsServiceRecord local = srvRecord.record;
+            final MdnsServiceRecord other = (MdnsServiceRecord) record;
+            // Note "equals" does not consider TTL or receipt time, as intended here
+            if (Objects.equals(local, other)) {
+                return false;
             }
         }
+
+        if (record instanceof MdnsTextRecord) {
+            final MdnsTextRecord local = registration.txtRecord.record;
+            final MdnsTextRecord other = (MdnsTextRecord) record;
+            if (Objects.equals(local, other)) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    private boolean conflictForHost(
+            @NonNull MdnsRecord record, @NonNull ServiceRegistration registration) {
+        // Only custom hosts are checked. When using the default host, the hostname is derived from
+        // a UUID and it's supposed to be unique.
+        if (registration.serviceInfo.getHostname() == null) {
+            return false;
+        }
+
+        // The record's name cannot be registered by NsdManager so it's not a conflict.
+        if (record.getName().length != 2 || !record.getName()[1].equals(LOCAL_TLD)) {
+            return false;
+        }
+
+        // Different names. There won't be a conflict.
+        if (!MdnsUtils.equalsIgnoreDnsCase(
+                record.getName()[0], registration.serviceInfo.getHostname())) {
+            return false;
+        }
+
+        // If this registration has any address record and there's no identical record in the
+        // repository, it's a conflict. There will be no conflict if no registration has addresses
+        // for that hostname.
+        if (record instanceof MdnsInetAddressRecord) {
+            if (!registration.addressRecords.isEmpty()) {
+                return !hasInetAddressRecord((MdnsInetAddressRecord) record);
+            }
+        }
+
+        return false;
+    }
+
+    private List<RecordInfo<MdnsInetAddressRecord>> getInetAddressRecordsForHostname(
+            @Nullable String hostname) {
+        List<RecordInfo<MdnsInetAddressRecord>> records = new ArrayList<>();
+        if (TextUtils.isEmpty(hostname)) {
+            forEachAddressRecord(mGeneralRecords, records::add);
+        } else {
+            forEachActiveServiceRegistrationWithHostname(
+                    hostname,
+                    (id, service) -> {
+                        if (service.isProbing) return;
+                        records.addAll(service.addressRecords);
+                    });
+        }
         return records;
     }
 
+    private List<MdnsInetAddressRecord> makeProbingInetAddressRecords(
+            @NonNull NsdServiceInfo serviceInfo) {
+        final List<MdnsInetAddressRecord> records = new ArrayList<>();
+        if (TextUtils.isEmpty(serviceInfo.getHostname())) {
+            if (mMdnsFeatureFlags.mIncludeInetAddressRecordsInProbing) {
+                forEachAddressRecord(mGeneralRecords, r -> records.add(r.record));
+            }
+        } else {
+            forEachActiveServiceRegistrationWithHostname(
+                    serviceInfo.getHostname(),
+                    (id, service) -> {
+                        for (RecordInfo<MdnsInetAddressRecord> recordInfo :
+                                service.addressRecords) {
+                            records.add(recordInfo.record);
+                        }
+                    });
+        }
+        return records;
+    }
+
+    private static void forEachAddressRecord(
+            List<RecordInfo<?>> records, Consumer<RecordInfo<MdnsInetAddressRecord>> consumer) {
+        for (RecordInfo<?> record : records) {
+            if (record.record instanceof MdnsInetAddressRecord) {
+                consumer.accept((RecordInfo<MdnsInetAddressRecord>) record);
+            }
+        }
+    }
+
+    private void forEachActiveServiceRegistrationWithHostname(
+            @NonNull String hostname, BiConsumer<Integer, ServiceRegistration> consumer) {
+        for (int i = 0; i < mServices.size(); ++i) {
+            int id = mServices.keyAt(i);
+            ServiceRegistration service = mServices.valueAt(i);
+            if (service.exiting) continue;
+            if (MdnsUtils.equalsIgnoreDnsCase(service.serviceInfo.getHostname(), hostname)) {
+                consumer.accept(id, service);
+            }
+        }
+    }
+
     /**
      * (Re)set a service to the probing state.
      * @return The {@link MdnsProber.ProbingInfo} to send for probing.
@@ -984,8 +1174,8 @@
         if (registration == null) return null;
 
         registration.setProbing(true);
-        return makeProbingInfo(
-                serviceId, registration.srvRecord.record, makeProbingInetAddressRecords());
+
+        return makeProbingInfo(serviceId, registration);
     }
 
     /**
@@ -1021,8 +1211,7 @@
         final ServiceRegistration newService = new ServiceRegistration(mDeviceHostname, newInfo,
                 existing.repliedServiceCount, existing.sentPacketCount);
         mServices.put(serviceId, newService);
-        return makeProbingInfo(
-                serviceId, newService.srvRecord.record, makeProbingInetAddressRecords());
+        return makeProbingInfo(serviceId, newService);
     }
 
     /**
diff --git a/service-t/src/com/android/server/connectivity/mdns/util/MdnsUtils.java b/service-t/src/com/android/server/connectivity/mdns/util/MdnsUtils.java
index 8fc8114..d553210 100644
--- a/service-t/src/com/android/server/connectivity/mdns/util/MdnsUtils.java
+++ b/service-t/src/com/android/server/connectivity/mdns/util/MdnsUtils.java
@@ -86,7 +86,10 @@
     /**
      * Compare two strings by DNS case-insensitive lowercase.
      */
-    public static boolean equalsIgnoreDnsCase(@NonNull String a, @NonNull String b) {
+    public static boolean equalsIgnoreDnsCase(@Nullable String a, @Nullable String b) {
+        if (a == null || b == null) {
+            return a == null && b == null;
+        }
         if (a.length() != b.length()) return false;
         for (int i = 0; i < a.length(); i++) {
             if (toDnsLowerCase(a.charAt(i)) != toDnsLowerCase(b.charAt(i))) {
diff --git a/tests/common/java/android/net/nsd/NsdServiceInfoTest.java b/tests/common/java/android/net/nsd/NsdServiceInfoTest.java
index 79c4980..8e89037 100644
--- a/tests/common/java/android/net/nsd/NsdServiceInfoTest.java
+++ b/tests/common/java/android/net/nsd/NsdServiceInfoTest.java
@@ -119,6 +119,7 @@
         fullInfo.setSubtypes(Set.of("_thread", "_matter"));
         fullInfo.setPort(4242);
         fullInfo.setHostAddresses(List.of(IPV4_ADDRESS));
+        fullInfo.setHostname("home");
         fullInfo.setNetwork(new Network(123));
         fullInfo.setInterfaceIndex(456);
         checkParcelable(fullInfo);
@@ -134,6 +135,7 @@
         attributedInfo.setServiceType("_kitten._tcp");
         attributedInfo.setPort(4242);
         attributedInfo.setHostAddresses(List.of(IPV6_ADDRESS, IPV4_ADDRESS));
+        attributedInfo.setHostname("home");
         attributedInfo.setAttribute("color", "pink");
         attributedInfo.setAttribute("sound", (new String("にゃあ")).getBytes("UTF-8"));
         attributedInfo.setAttribute("adorable", (String) null);
@@ -169,6 +171,7 @@
         assertEquals(original.getServiceName(), result.getServiceName());
         assertEquals(original.getServiceType(), result.getServiceType());
         assertEquals(original.getHost(), result.getHost());
+        assertEquals(original.getHostname(), result.getHostname());
         assertTrue(original.getPort() == result.getPort());
         assertEquals(original.getNetwork(), result.getNetwork());
         assertEquals(original.getInterfaceIndex(), result.getInterfaceIndex());
diff --git a/tests/cts/net/src/android/net/cts/NsdManagerTest.kt b/tests/cts/net/src/android/net/cts/NsdManagerTest.kt
index 8f9f8c7..c368d5b 100644
--- a/tests/cts/net/src/android/net/cts/NsdManagerTest.kt
+++ b/tests/cts/net/src/android/net/cts/NsdManagerTest.kt
@@ -127,6 +127,7 @@
 import org.junit.Rule
 import org.junit.Test
 import org.junit.runner.RunWith
+import kotlin.test.assertNotEquals
 
 private const val TAG = "NsdManagerTest"
 private const val TIMEOUT_MS = 2000L
@@ -162,7 +163,11 @@
     private val cm by lazy { context.getSystemService(ConnectivityManager::class.java)!! }
     private val serviceName = "NsdTest%09d".format(Random().nextInt(1_000_000_000))
     private val serviceName2 = "NsdTest%09d".format(Random().nextInt(1_000_000_000))
+    private val serviceName3 = "NsdTest%09d".format(Random().nextInt(1_000_000_000))
     private val serviceType = "_nmt%09d._tcp".format(Random().nextInt(1_000_000_000))
+    private val serviceType2 = "_nmt%09d._tcp".format(Random().nextInt(1_000_000_000))
+    private val customHostname = "NsdTestHost%09d".format(Random().nextInt(1_000_000_000))
+    private val customHostname2 = "NsdTestHost%09d".format(Random().nextInt(1_000_000_000))
     private val handlerThread = HandlerThread(NsdManagerTest::class.java.simpleName)
     private val ctsNetUtils by lazy{ CtsNetUtils(context) }
 
@@ -1189,6 +1194,84 @@
     }
 
     @Test
+    fun testRegisterServiceWithCustomHostAndAddresses_conflictDuringProbing_hostRenamed() {
+        val si = makeTestServiceInfo(testNetwork1.network).apply {
+            hostname = customHostname
+            hostAddresses = listOf(
+                    parseNumericAddress("192.0.2.24"),
+                    parseNumericAddress("2001:db8::3"))
+        }
+
+        val packetReader = TapPacketReader(Handler(handlerThread.looper),
+                testNetwork1.iface.fileDescriptor.fileDescriptor, 1500 /* maxPacketSize */)
+        packetReader.startAsyncForTest()
+        handlerThread.waitForIdle(TIMEOUT_MS)
+
+        // Register service on testNetwork1
+        val registrationRecord = NsdRegistrationRecord()
+        nsdManager.registerService(si, NsdManager.PROTOCOL_DNS_SD, { it.run() },
+                registrationRecord)
+
+        tryTest {
+            assertNotNull(packetReader.pollForProbe(serviceName, serviceType),
+                    "Did not find a probe for the service")
+            packetReader.sendResponse(buildConflictingAnnouncementForCustomHost())
+
+            // Registration must use an updated hostname to avoid the conflict
+            val cb = registrationRecord.expectCallback<ServiceRegistered>(REGISTRATION_TIMEOUT_MS)
+            // Service name is not renamed because there's no conflict on the service name.
+            // TODO: b/283053491 - enable this check
+//            assertEquals(serviceName, cb.serviceInfo.serviceName)
+            val hostname = cb.serviceInfo.hostname ?: fail("Missing hostname")
+            hostname.let {
+                assertTrue("Unexpected registered hostname: $it",
+                        it.startsWith(customHostname) && it != customHostname)
+            }
+        } cleanupStep {
+            nsdManager.unregisterService(registrationRecord)
+            registrationRecord.expectCallback<ServiceUnregistered>()
+        } cleanup {
+            packetReader.handler.post { packetReader.stop() }
+            handlerThread.waitForIdle(TIMEOUT_MS)
+        }
+    }
+
+    @Test
+    fun testRegisterServiceWithCustomHostNoAddresses_noConflictDuringProbing_notRenamed() {
+        val si = makeTestServiceInfo(testNetwork1.network).apply {
+            hostname = customHostname
+        }
+
+        val packetReader = TapPacketReader(Handler(handlerThread.looper),
+                testNetwork1.iface.fileDescriptor.fileDescriptor, 1500 /* maxPacketSize */)
+        packetReader.startAsyncForTest()
+        handlerThread.waitForIdle(TIMEOUT_MS)
+
+        // Register service on testNetwork1
+        val registrationRecord = NsdRegistrationRecord()
+        nsdManager.registerService(si, NsdManager.PROTOCOL_DNS_SD, { it.run() },
+                registrationRecord)
+
+        tryTest {
+            assertNotNull(packetReader.pollForProbe(serviceName, serviceType),
+                    "Did not find a probe for the service")
+            // Not a conflict because no record is registered for the hostname
+            packetReader.sendResponse(buildConflictingAnnouncementForCustomHost())
+
+            // Registration is not renamed because there's no conflict
+            val cb = registrationRecord.expectCallback<ServiceRegistered>(REGISTRATION_TIMEOUT_MS)
+            assertEquals(serviceName, cb.serviceInfo.serviceName)
+            assertEquals(customHostname, cb.serviceInfo.hostname)
+        } cleanupStep {
+            nsdManager.unregisterService(registrationRecord)
+            registrationRecord.expectCallback<ServiceUnregistered>()
+        } cleanup {
+            packetReader.handler.post { packetReader.stop() }
+            handlerThread.waitForIdle(TIMEOUT_MS)
+        }
+    }
+
+    @Test
     fun testRegisterWithConflictAfterProbing() {
         // This test requires shims supporting T+ APIs (NsdServiceInfo.network)
         assumeTrue(TestUtils.shouldTestTApis())
@@ -1263,6 +1346,52 @@
         }
     }
 
+    // TODO: b/322282952 - Add the test case that the hostname is renamed due to a conflict after
+    //  probing succeeded.
+
+    @Test
+    fun testRegisterServiceWithCustomHostNoAddresses_noConflictAfterProbing_notRenamed() {
+        val si = makeTestServiceInfo(testNetwork1.network).apply {
+            hostname = customHostname
+        }
+
+        // Register service on testNetwork1
+        val registrationRecord = NsdRegistrationRecord()
+        val discoveryRecord = NsdDiscoveryRecord()
+        val registeredService = registerService(registrationRecord, si)
+        val packetReader = TapPacketReader(Handler(handlerThread.looper),
+                testNetwork1.iface.fileDescriptor.fileDescriptor, 1500 /* maxPacketSize */)
+        packetReader.startAsyncForTest()
+        handlerThread.waitForIdle(TIMEOUT_MS)
+
+        tryTest {
+            assertNotNull(packetReader.pollForAdvertisement(serviceName, serviceType),
+                    "No announcements sent after initial probing")
+
+            assertEquals(si.serviceName, registeredService.serviceName)
+            assertEquals(si.hostname, registeredService.hostname)
+
+            // Send a conflicting announcement
+            val conflictingAnnouncement = buildConflictingAnnouncementForCustomHost()
+            packetReader.sendResponse(conflictingAnnouncement)
+
+            nsdManager.discoverServices(serviceType, NsdManager.PROTOCOL_DNS_SD,
+                    testNetwork1.network, { it.run() }, discoveryRecord)
+
+            // The service is not renamed
+            discoveryRecord.waitForServiceDiscovered(si.serviceName, serviceType)
+        } cleanupStep {
+            nsdManager.stopServiceDiscovery(discoveryRecord)
+            discoveryRecord.expectCallback<DiscoveryStopped>()
+        } cleanupStep {
+            nsdManager.unregisterService(registrationRecord)
+            registrationRecord.expectCallback<ServiceUnregistered>()
+        } cleanup {
+            packetReader.handler.post { packetReader.stop() }
+            handlerThread.waitForIdle(TIMEOUT_MS)
+        }
+    }
+
     // Test that even if only a PTR record is received as a reply when discovering, without the
     // SRV, TXT, address records as recommended (but not mandated) by RFC 6763 12, the service can
     // still be discovered.
@@ -1447,6 +1576,212 @@
         return Inet6Address.getByAddress(addrBytes) as Inet6Address
     }
 
+    @Test
+    fun testAdvertisingAndDiscovery_servicesWithCustomHost_customHostAddressesFound() {
+        val hostAddresses1 = listOf(
+                parseNumericAddress("192.0.2.23"),
+                parseNumericAddress("2001:db8::1"),
+                parseNumericAddress("2001:db8::2"))
+        val hostAddresses2 = listOf(
+                parseNumericAddress("192.0.2.24"),
+                parseNumericAddress("2001:db8::3"))
+        val si1 = NsdServiceInfo().also {
+            it.network = testNetwork1.network
+            it.serviceName = serviceName
+            it.serviceType = serviceType
+            it.port = TEST_PORT
+            it.hostname = customHostname
+            it.hostAddresses = hostAddresses1
+        }
+        val si2 = NsdServiceInfo().also {
+            it.network = testNetwork1.network
+            it.serviceName = serviceName2
+            it.serviceType = serviceType
+            it.port = TEST_PORT + 1
+            it.hostname = customHostname2
+            it.hostAddresses = hostAddresses2
+        }
+        val registrationRecord1 = NsdRegistrationRecord()
+        val registrationRecord2 = NsdRegistrationRecord()
+
+        val discoveryRecord1 = NsdDiscoveryRecord()
+        val discoveryRecord2 = NsdDiscoveryRecord()
+        tryTest {
+            registerService(registrationRecord1, si1)
+
+            nsdManager.discoverServices(serviceType, NsdManager.PROTOCOL_DNS_SD,
+                    testNetwork1.network, Executor { it.run() }, discoveryRecord1)
+
+            val discoveredInfo = discoveryRecord1.waitForServiceDiscovered(
+                    serviceName, serviceType, testNetwork1.network)
+            val resolvedInfo = resolveService(discoveredInfo)
+
+            assertEquals(TEST_PORT, resolvedInfo.port)
+            assertEquals(si1.hostname, resolvedInfo.hostname)
+            assertAddressEquals(hostAddresses1, resolvedInfo.hostAddresses)
+
+            registerService(registrationRecord2, si2)
+            nsdManager.discoverServices(serviceType, NsdManager.PROTOCOL_DNS_SD,
+                    testNetwork1.network, Executor { it.run() }, discoveryRecord2)
+
+            val discoveredInfo2 = discoveryRecord2.waitForServiceDiscovered(
+                    serviceName2, serviceType, testNetwork1.network)
+            val resolvedInfo2 = resolveService(discoveredInfo2)
+
+            assertEquals(TEST_PORT + 1, resolvedInfo2.port)
+            assertEquals(si2.hostname, resolvedInfo2.hostname)
+            assertAddressEquals(hostAddresses2, resolvedInfo2.hostAddresses)
+        } cleanupStep {
+            nsdManager.stopServiceDiscovery(discoveryRecord1)
+            nsdManager.stopServiceDiscovery(discoveryRecord2)
+
+            discoveryRecord1.expectCallbackEventually<DiscoveryStopped>()
+            discoveryRecord2.expectCallbackEventually<DiscoveryStopped>()
+        } cleanup {
+            nsdManager.unregisterService(registrationRecord1)
+            nsdManager.unregisterService(registrationRecord2)
+        }
+    }
+
+    @Test
+    fun testAdvertisingAndDiscovery_multipleRegistrationsForSameCustomHost_unionOfAddressesFound() {
+        val hostAddresses1 = listOf(
+                parseNumericAddress("192.0.2.23"),
+                parseNumericAddress("2001:db8::1"),
+                parseNumericAddress("2001:db8::2"))
+        val hostAddresses2 = listOf(
+                parseNumericAddress("192.0.2.24"),
+                parseNumericAddress("2001:db8::3"))
+        val hostAddresses3 = listOf(
+                parseNumericAddress("2001:db8::3"),
+                parseNumericAddress("2001:db8::5"))
+        val si1 = NsdServiceInfo().also {
+            it.network = testNetwork1.network
+            it.hostname = customHostname
+            it.hostAddresses = hostAddresses1
+        }
+        val si2 = NsdServiceInfo().also {
+            it.network = testNetwork1.network
+            it.serviceName = serviceName
+            it.serviceType = serviceType
+            it.port = TEST_PORT
+            it.hostname = customHostname
+            it.hostAddresses = hostAddresses2
+        }
+        val si3 = NsdServiceInfo().also {
+            it.network = testNetwork1.network
+            it.serviceName = serviceName3
+            it.serviceType = serviceType
+            it.port = TEST_PORT + 1
+            it.hostname = customHostname
+            it.hostAddresses = hostAddresses3
+        }
+
+        val registrationRecord1 = NsdRegistrationRecord()
+        val registrationRecord2 = NsdRegistrationRecord()
+        val registrationRecord3 = NsdRegistrationRecord()
+
+        val discoveryRecord = NsdDiscoveryRecord()
+        tryTest {
+            registerService(registrationRecord1, si1)
+            registerService(registrationRecord2, si2)
+
+            nsdManager.discoverServices(serviceType, NsdManager.PROTOCOL_DNS_SD,
+                    testNetwork1.network, Executor { it.run() }, discoveryRecord)
+
+            val discoveredInfo1 = discoveryRecord.waitForServiceDiscovered(
+                    serviceName, serviceType, testNetwork1.network)
+            val resolvedInfo1 = resolveService(discoveredInfo1)
+
+            assertEquals(TEST_PORT, resolvedInfo1.port)
+            assertEquals(si1.hostname, resolvedInfo1.hostname)
+            assertAddressEquals(
+                    hostAddresses1 + hostAddresses2,
+                    resolvedInfo1.hostAddresses)
+
+            registerService(registrationRecord3, si3)
+
+            val discoveredInfo2 = discoveryRecord.waitForServiceDiscovered(
+                    serviceName3, serviceType, testNetwork1.network)
+            val resolvedInfo2 = resolveService(discoveredInfo2)
+
+            assertEquals(TEST_PORT + 1, resolvedInfo2.port)
+            assertEquals(si2.hostname, resolvedInfo2.hostname)
+            assertAddressEquals(
+                    hostAddresses1 + hostAddresses2 + hostAddresses3,
+                    resolvedInfo2.hostAddresses)
+        } cleanupStep {
+            nsdManager.stopServiceDiscovery(discoveryRecord)
+
+            discoveryRecord.expectCallbackEventually<DiscoveryStopped>()
+        } cleanup {
+            nsdManager.unregisterService(registrationRecord1)
+            nsdManager.unregisterService(registrationRecord2)
+            nsdManager.unregisterService(registrationRecord3)
+        }
+    }
+
+    @Test
+    fun testAdvertisingAndDiscovery_servicesWithTheSameCustomHostAddressOmitted_addressesFound() {
+        val hostAddresses = listOf(
+                parseNumericAddress("192.0.2.23"),
+                parseNumericAddress("2001:db8::1"),
+                parseNumericAddress("2001:db8::2"))
+        val si1 = NsdServiceInfo().also {
+            it.network = testNetwork1.network
+            it.serviceType = serviceType
+            it.serviceName = serviceName
+            it.port = TEST_PORT
+            it.hostname = customHostname
+            it.hostAddresses = hostAddresses
+        }
+        val si2 = NsdServiceInfo().also {
+            it.network = testNetwork1.network
+            it.serviceType = serviceType
+            it.serviceName = serviceName2
+            it.port = TEST_PORT + 1
+            it.hostname = customHostname
+        }
+
+        val registrationRecord1 = NsdRegistrationRecord()
+        val registrationRecord2 = NsdRegistrationRecord()
+
+        val discoveryRecord = NsdDiscoveryRecord()
+        tryTest {
+            registerService(registrationRecord1, si1)
+
+            nsdManager.discoverServices(serviceType, NsdManager.PROTOCOL_DNS_SD,
+                    testNetwork1.network, Executor { it.run() }, discoveryRecord)
+
+            val discoveredInfo1 = discoveryRecord.waitForServiceDiscovered(
+                    serviceName, serviceType, testNetwork1.network)
+            val resolvedInfo1 = resolveService(discoveredInfo1)
+
+            assertEquals(serviceName, discoveredInfo1.serviceName)
+            assertEquals(TEST_PORT, resolvedInfo1.port)
+            assertEquals(si1.hostname, resolvedInfo1.hostname)
+            assertAddressEquals(hostAddresses, resolvedInfo1.hostAddresses)
+
+            registerService(registrationRecord2, si2)
+
+            val discoveredInfo2 = discoveryRecord.waitForServiceDiscovered(
+                    serviceName2, serviceType, testNetwork1.network)
+            val resolvedInfo2 = resolveService(discoveredInfo2)
+
+            assertEquals(serviceName2, discoveredInfo2.serviceName)
+            assertEquals(TEST_PORT + 1, resolvedInfo2.port)
+            assertEquals(si2.hostname, resolvedInfo2.hostname)
+            assertAddressEquals(hostAddresses, resolvedInfo2.hostAddresses)
+        } cleanupStep {
+            nsdManager.stopServiceDiscovery(discoveryRecord)
+
+            discoveryRecord.expectCallback<DiscoveryStopped>()
+        } cleanup {
+            nsdManager.unregisterService(registrationRecord1)
+            nsdManager.unregisterService(registrationRecord2)
+        }
+    }
+
     private fun buildConflictingAnnouncement(): ByteBuffer {
         /*
         Generated with:
@@ -1463,6 +1798,22 @@
         return buildMdnsPacket(mdnsPayload)
     }
 
+    private fun buildConflictingAnnouncementForCustomHost(): ByteBuffer {
+        /*
+        Generated with scapy:
+        raw(DNS(rd=0, qr=1, aa=1, qd = None, an =
+            DNSRR(rrname='NsdTestHost123456789.local', type=28, rclass=1, ttl=120,
+                    rdata='2001:db8::321')
+        )).hex()
+         */
+        val mdnsPayload = HexDump.hexStringToByteArray("000084000000000100000000144e7364" +
+                "54657374486f7374313233343536373839056c6f63616c00001c000100000078001020010db80000" +
+                "00000000000000000321")
+        replaceCustomHostnameWithTestSuffix(mdnsPayload)
+
+        return buildMdnsPacket(mdnsPayload)
+    }
+
     /**
      * Replaces occurrences of "NsdTest123456789" and "_nmt123456789" in mDNS payload with the
      * actual random name and type that are used by the test.
@@ -1479,6 +1830,19 @@
         replaceAll(packetBuffer, testPacketTypePrefix, encodedTypePrefix)
     }
 
+    /**
+     * Replaces occurrences of "NsdTestHost123456789" in mDNS payload with the
+     * actual random host name that are used by the test.
+     */
+    private fun replaceCustomHostnameWithTestSuffix(mdnsPayload: ByteArray) {
+        // Test custom hostnames have consistent length and are always ASCII
+        val testPacketName = "NsdTestHost123456789".encodeToByteArray()
+        val encodedHostname = customHostname.encodeToByteArray()
+
+        val packetBuffer = ByteBuffer.wrap(mdnsPayload)
+        replaceAll(packetBuffer, testPacketName, encodedHostname)
+    }
+
     private tailrec fun replaceAll(buffer: ByteBuffer, source: ByteArray, replacement: ByteArray) {
         assertEquals(source.size, replacement.size)
         val index = buffer.array().indexOf(source)
@@ -1577,3 +1941,9 @@
     if (this == null) return ""
     return String(this, StandardCharsets.UTF_8)
 }
+
+private fun assertAddressEquals(expected: List<InetAddress>, actual: List<InetAddress>) {
+    // No duplicate addresses in the actual address list
+    assertEquals(actual.toSet().size, actual.size)
+    assertEquals(expected.toSet(), actual.toSet())
+}
\ No newline at end of file
diff --git a/tests/unit/java/android/net/nsd/NsdManagerTest.java b/tests/unit/java/android/net/nsd/NsdManagerTest.java
index aabe8d3..951675c 100644
--- a/tests/unit/java/android/net/nsd/NsdManagerTest.java
+++ b/tests/unit/java/android/net/nsd/NsdManagerTest.java
@@ -52,6 +52,9 @@
 import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 
+import java.net.InetAddress;
+import java.util.List;
+
 @DevSdkIgnoreRunner.MonitorThreadLeak
 @RunWith(DevSdkIgnoreRunner.class)
 @SmallTest
@@ -370,6 +373,9 @@
         NsdManager.RegistrationListener listener1 = mock(NsdManager.RegistrationListener.class);
         NsdManager.DiscoveryListener listener2 = mock(NsdManager.DiscoveryListener.class);
         NsdManager.ResolveListener listener3 = mock(NsdManager.ResolveListener.class);
+        NsdManager.RegistrationListener listener4 = mock(NsdManager.RegistrationListener.class);
+        NsdManager.RegistrationListener listener5 = mock(NsdManager.RegistrationListener.class);
+        NsdManager.RegistrationListener listener6 = mock(NsdManager.RegistrationListener.class);
 
         NsdServiceInfo invalidService = new NsdServiceInfo(null, null);
         NsdServiceInfo validService = new NsdServiceInfo("a_name", "_a_type._tcp");
@@ -379,6 +385,7 @@
                 "_a_type._tcp,_sub1,_s2");
         NsdServiceInfo otherSubtypeUpdate = new NsdServiceInfo("a_name", "_a_type._tcp,_sub1,_s3");
         NsdServiceInfo dotSyntaxSubtypeUpdate = new NsdServiceInfo("a_name", "_sub1._a_type._tcp");
+
         validService.setPort(2222);
         otherServiceWithSubtype.setPort(2222);
         validServiceDuplicate.setPort(2222);
@@ -386,6 +393,33 @@
         otherSubtypeUpdate.setPort(2222);
         dotSyntaxSubtypeUpdate.setPort(2222);
 
+        NsdServiceInfo invalidMissingHostnameWithAddresses = new NsdServiceInfo(null, null);
+        invalidMissingHostnameWithAddresses.setHostAddresses(
+                List.of(
+                        InetAddress.parseNumericAddress("192.168.82.14"),
+                        InetAddress.parseNumericAddress("2001::1")));
+
+        NsdServiceInfo validCustomHostWithAddresses = new NsdServiceInfo(null, null);
+        validCustomHostWithAddresses.setHostname("a_host");
+        validCustomHostWithAddresses.setHostAddresses(
+                List.of(
+                        InetAddress.parseNumericAddress("192.168.82.14"),
+                        InetAddress.parseNumericAddress("2001::1")));
+
+        NsdServiceInfo validServiceWithCustomHostAndAddresses =
+                new NsdServiceInfo("a_name", "_a_type._tcp");
+        validServiceWithCustomHostAndAddresses.setPort(2222);
+        validServiceWithCustomHostAndAddresses.setHostname("a_host");
+        validServiceWithCustomHostAndAddresses.setHostAddresses(
+                List.of(
+                        InetAddress.parseNumericAddress("192.168.82.14"),
+                        InetAddress.parseNumericAddress("2001::1")));
+
+        NsdServiceInfo validServiceWithCustomHostNoAddresses =
+                new NsdServiceInfo("a_name", "_a_type._tcp");
+        validServiceWithCustomHostNoAddresses.setPort(2222);
+        validServiceWithCustomHostNoAddresses.setHostname("a_host");
+
         // Service registration
         //  - invalid arguments
         mustFail(() -> { manager.unregisterService(null); });
@@ -394,6 +428,8 @@
         mustFail(() -> { manager.registerService(invalidService, PROTOCOL, listener1); });
         mustFail(() -> { manager.registerService(validService, -1, listener1); });
         mustFail(() -> { manager.registerService(validService, PROTOCOL, null); });
+        mustFail(() -> {
+            manager.registerService(invalidMissingHostnameWithAddresses, PROTOCOL, listener1); });
         manager.registerService(validService, PROTOCOL, listener1);
         //  - update without subtype is not allowed
         mustFail(() -> { manager.registerService(validServiceDuplicate, PROTOCOL, listener1); });
@@ -415,6 +451,15 @@
         // TODO: make listener immediately reusable
         //mustFail(() -> { manager.unregisterService(listener1); });
         //manager.registerService(validService, PROTOCOL, listener1);
+        //  - registering a custom host without a service is valid
+        manager.registerService(validCustomHostWithAddresses, PROTOCOL, listener4);
+        manager.unregisterService(listener4);
+        //  - registering a service with a custom host is valid
+        manager.registerService(validServiceWithCustomHostAndAddresses, PROTOCOL, listener5);
+        manager.unregisterService(listener5);
+        //  - registering a service with a custom host with no addresses is valid
+        manager.registerService(validServiceWithCustomHostNoAddresses, PROTOCOL, listener6);
+        manager.unregisterService(listener6);
 
         // Discover service
         //  - invalid arguments
diff --git a/tests/unit/java/com/android/server/NsdServiceTest.java b/tests/unit/java/com/android/server/NsdServiceTest.java
index a17197e..b60f0b4 100644
--- a/tests/unit/java/com/android/server/NsdServiceTest.java
+++ b/tests/unit/java/com/android/server/NsdServiceTest.java
@@ -1139,7 +1139,7 @@
         verify(mAdvertiser).addOrUpdateService(anyInt(), argThat(s ->
                 "Instance".equals(s.getServiceName())
                         && SERVICE_TYPE.equals(s.getServiceType())
-                        && s.getSubtypes().equals(Set.of("_subtype"))), any());
+                        && s.getSubtypes().equals(Set.of("_subtype"))), any(), anyInt());
 
         final DiscoveryListener discListener = mock(DiscoveryListener.class);
         client.discoverServices(typeWithSubtype, PROTOCOL, network, Runnable::run, discListener);
@@ -1246,7 +1246,7 @@
 
         final ArgumentCaptor<Integer> serviceIdCaptor = ArgumentCaptor.forClass(Integer.class);
         verify(mAdvertiser).addOrUpdateService(serviceIdCaptor.capture(),
-                argThat(info -> matches(info, regInfo)), any());
+                argThat(info -> matches(info, regInfo)), any(), anyInt());
 
         client.unregisterService(regListenerWithoutFeature);
         waitForIdle();
@@ -1275,7 +1275,7 @@
         service1.setHostAddresses(List.of(parseNumericAddress("2001:db8::123")));
         service1.setPort(1234);
         final NsdServiceInfo service2 = new NsdServiceInfo(SERVICE_NAME, "_type2._tcp");
-        service2.setHostAddresses(List.of(parseNumericAddress("2001:db8::123")));
+        service1.setHostAddresses(List.of(parseNumericAddress("2001:db8::123")));
         service2.setPort(1234);
 
         client.discoverServices(service1.getServiceType(),
@@ -1307,9 +1307,9 @@
 
         // The advertiser is enabled for _type2 but not _type1
         verify(mAdvertiser, never()).addOrUpdateService(anyInt(),
-                argThat(info -> matches(info, service1)), any());
+                argThat(info -> matches(info, service1)), any(), anyInt());
         verify(mAdvertiser).addOrUpdateService(anyInt(), argThat(info -> matches(info, service2)),
-                any());
+                any(), anyInt());
     }
 
     @Test
@@ -1334,7 +1334,7 @@
         verify(mSocketProvider).startMonitoringSockets();
         final ArgumentCaptor<Integer> idCaptor = ArgumentCaptor.forClass(Integer.class);
         verify(mAdvertiser).addOrUpdateService(idCaptor.capture(), argThat(info ->
-                matches(info, regInfo)), any());
+                matches(info, regInfo)), any(), anyInt());
 
         // Verify onServiceRegistered callback
         final MdnsAdvertiser.AdvertiserCallback cb = cbCaptor.getValue();
@@ -1382,7 +1382,7 @@
 
         client.registerService(regInfo, NsdManager.PROTOCOL_DNS_SD, Runnable::run, regListener);
         waitForIdle();
-        verify(mAdvertiser, never()).addOrUpdateService(anyInt(), any(), any());
+        verify(mAdvertiser, never()).addOrUpdateService(anyInt(), any(), any(), anyInt());
 
         verify(regListener, timeout(TIMEOUT_MS)).onRegistrationFailed(
                 argThat(info -> matches(info, regInfo)), eq(FAILURE_INTERNAL_ERROR));
@@ -1411,8 +1411,12 @@
         waitForIdle();
         final ArgumentCaptor<Integer> idCaptor = ArgumentCaptor.forClass(Integer.class);
         // Service name is truncated to 63 characters
-        verify(mAdvertiser).addOrUpdateService(idCaptor.capture(),
-                argThat(info -> info.getServiceName().equals("a".repeat(63))), any());
+        verify(mAdvertiser)
+                .addOrUpdateService(
+                        idCaptor.capture(),
+                        argThat(info -> info.getServiceName().equals("a".repeat(63))),
+                        any(),
+                        anyInt());
 
         // Verify onServiceRegistered callback
         final MdnsAdvertiser.AdvertiserCallback cb = cbCaptor.getValue();
@@ -1510,7 +1514,7 @@
         client.registerService(regInfo, NsdManager.PROTOCOL_DNS_SD, Runnable::run, regListener);
         waitForIdle();
         verify(mSocketProvider).startMonitoringSockets();
-        verify(mAdvertiser).addOrUpdateService(anyInt(), any(), any());
+        verify(mAdvertiser).addOrUpdateService(anyInt(), any(), any(), anyInt());
 
         // Verify the discovery uses MdnsDiscoveryManager
         final DiscoveryListener discListener = mock(DiscoveryListener.class);
@@ -1543,7 +1547,7 @@
         client.registerService(regInfo, NsdManager.PROTOCOL_DNS_SD, Runnable::run, regListener);
         waitForIdle();
         verify(mSocketProvider).startMonitoringSockets();
-        verify(mAdvertiser).addOrUpdateService(anyInt(), any(), any());
+        verify(mAdvertiser).addOrUpdateService(anyInt(), any(), any(), anyInt());
 
         final Network wifiNetwork1 = new Network(123);
         final Network wifiNetwork2 = new Network(124);
diff --git a/tests/unit/java/com/android/server/connectivity/mdns/MdnsAdvertiserTest.kt b/tests/unit/java/com/android/server/connectivity/mdns/MdnsAdvertiserTest.kt
index 5c04362..f753c93 100644
--- a/tests/unit/java/com/android/server/connectivity/mdns/MdnsAdvertiserTest.kt
+++ b/tests/unit/java/com/android/server/connectivity/mdns/MdnsAdvertiserTest.kt
@@ -32,6 +32,7 @@
 import com.android.net.module.util.SharedLog
 import com.android.server.connectivity.ConnectivityResources
 import com.android.server.connectivity.mdns.MdnsAdvertiser.AdvertiserCallback
+import com.android.server.connectivity.mdns.MdnsInterfaceAdvertiser.CONFLICT_SERVICE
 import com.android.server.connectivity.mdns.MdnsSocketProvider.SocketCallback
 import com.android.testutils.DevSdkIgnoreRule.IgnoreUpTo
 import com.android.testutils.DevSdkIgnoreRunner
@@ -76,6 +77,7 @@
 private const val TEST_SUBTYPE2 = "_subtype2"
 private val TEST_INTERFACE1 = "test_iface1"
 private val TEST_INTERFACE2 = "test_iface2"
+private val TEST_CLIENT_UID_1 = 10010
 private val TEST_OFFLOAD_PACKET1 = byteArrayOf(0x01, 0x02, 0x03)
 private val TEST_OFFLOAD_PACKET2 = byteArrayOf(0x02, 0x03, 0x04)
 private val DEFAULT_ADVERTISING_OPTION = MdnsAdvertisingOptions.getDefaultOptions()
@@ -227,7 +229,7 @@
         val advertiser =
             MdnsAdvertiser(thread.looper, socketProvider, cb, mockDeps, sharedlog, flags, context)
         postSync { advertiser.addOrUpdateService(SERVICE_ID_1, SERVICE_1,
-                DEFAULT_ADVERTISING_OPTION) }
+                DEFAULT_ADVERTISING_OPTION, TEST_CLIENT_UID_1) }
 
         val socketCbCaptor = ArgumentCaptor.forClass(SocketCallback::class.java)
         verify(socketProvider).requestSocket(eq(TEST_NETWORK_1), socketCbCaptor.capture())
@@ -254,7 +256,10 @@
         verify(cb).onOffloadStartOrUpdate(eq(TEST_INTERFACE1), eq(OFFLOAD_SERVICEINFO_NO_SUBTYPE))
 
         // Service is conflicted.
-        postSync { intAdvCbCaptor.value.onServiceConflict(mockInterfaceAdvertiser1, SERVICE_ID_1) }
+        postSync {
+            intAdvCbCaptor.value
+                    .onServiceConflict(mockInterfaceAdvertiser1, SERVICE_ID_1, CONFLICT_SERVICE)
+        }
 
         // Verify the metrics data
         doReturn(25).`when`(mockInterfaceAdvertiser1).getServiceRepliedRequestsCount(SERVICE_ID_1)
@@ -289,7 +294,7 @@
         val advertiser =
             MdnsAdvertiser(thread.looper, socketProvider, cb, mockDeps, sharedlog, flags, context)
         postSync { advertiser.addOrUpdateService(SERVICE_ID_1, ALL_NETWORKS_SERVICE_SUBTYPE,
-                DEFAULT_ADVERTISING_OPTION) }
+                DEFAULT_ADVERTISING_OPTION, TEST_CLIENT_UID_1) }
 
         val socketCbCaptor = ArgumentCaptor.forClass(SocketCallback::class.java)
         verify(socketProvider).requestSocket(eq(ALL_NETWORKS_SERVICE_SUBTYPE.network),
@@ -327,9 +332,18 @@
                 argThat { it.matches(ALL_NETWORKS_SERVICE_SUBTYPE) })
 
         // Services are conflicted.
-        postSync { intAdvCbCaptor1.value.onServiceConflict(mockInterfaceAdvertiser1, SERVICE_ID_1) }
-        postSync { intAdvCbCaptor1.value.onServiceConflict(mockInterfaceAdvertiser1, SERVICE_ID_1) }
-        postSync { intAdvCbCaptor2.value.onServiceConflict(mockInterfaceAdvertiser2, SERVICE_ID_1) }
+        postSync {
+            intAdvCbCaptor1.value
+                    .onServiceConflict(mockInterfaceAdvertiser1, SERVICE_ID_1, CONFLICT_SERVICE)
+        }
+        postSync {
+            intAdvCbCaptor1.value
+                    .onServiceConflict(mockInterfaceAdvertiser1, SERVICE_ID_1, CONFLICT_SERVICE)
+        }
+        postSync {
+            intAdvCbCaptor2.value
+                    .onServiceConflict(mockInterfaceAdvertiser2, SERVICE_ID_1, CONFLICT_SERVICE)
+        }
 
         // Verify the metrics data
         doReturn(10).`when`(mockInterfaceAdvertiser1).getServiceRepliedRequestsCount(SERVICE_ID_1)
@@ -361,18 +375,19 @@
         val advertiser =
             MdnsAdvertiser(thread.looper, socketProvider, cb, mockDeps, sharedlog, flags, context)
         postSync {
-            advertiser.addOrUpdateService(SERVICE_ID_1, SERVICE_1, DEFAULT_ADVERTISING_OPTION)
+            advertiser.addOrUpdateService(SERVICE_ID_1, SERVICE_1, DEFAULT_ADVERTISING_OPTION,
+                    TEST_CLIENT_UID_1)
             advertiser.addOrUpdateService(SERVICE_ID_2,
                 NsdServiceInfo("TestService2", "_PRIORITYTEST._udp").apply {
                     port = 12345
                     hostAddresses = listOf(TEST_ADDR)
-                }, DEFAULT_ADVERTISING_OPTION)
+                }, DEFAULT_ADVERTISING_OPTION, TEST_CLIENT_UID_1)
             advertiser.addOrUpdateService(
                 SERVICE_ID_3,
                 NsdServiceInfo("TestService3", "_notprioritized._tcp").apply {
                     port = 12345
                     hostAddresses = listOf(TEST_ADDR)
-                }, DEFAULT_ADVERTISING_OPTION)
+                }, DEFAULT_ADVERTISING_OPTION, TEST_CLIENT_UID_1)
         }
 
         val socketCbCaptor = ArgumentCaptor.forClass(SocketCallback::class.java)
@@ -419,7 +434,7 @@
         val advertiser =
             MdnsAdvertiser(thread.looper, socketProvider, cb, mockDeps, sharedlog, flags, context)
         postSync { advertiser.addOrUpdateService(SERVICE_ID_1, SERVICE_1,
-                DEFAULT_ADVERTISING_OPTION) }
+                DEFAULT_ADVERTISING_OPTION, TEST_CLIENT_UID_1) }
 
         val oneNetSocketCbCaptor = ArgumentCaptor.forClass(SocketCallback::class.java)
         verify(socketProvider).requestSocket(eq(TEST_NETWORK_1), oneNetSocketCbCaptor.capture())
@@ -427,18 +442,18 @@
 
         // Register a service with the same name on all networks (name conflict)
         postSync { advertiser.addOrUpdateService(SERVICE_ID_2, ALL_NETWORKS_SERVICE,
-                DEFAULT_ADVERTISING_OPTION) }
+                DEFAULT_ADVERTISING_OPTION, TEST_CLIENT_UID_1) }
         val allNetSocketCbCaptor = ArgumentCaptor.forClass(SocketCallback::class.java)
         verify(socketProvider).requestSocket(eq(null), allNetSocketCbCaptor.capture())
         val allNetSocketCb = allNetSocketCbCaptor.value
 
         postSync { advertiser.addOrUpdateService(LONG_SERVICE_ID_1, LONG_SERVICE_1,
-                DEFAULT_ADVERTISING_OPTION) }
+                DEFAULT_ADVERTISING_OPTION, TEST_CLIENT_UID_1) }
         postSync { advertiser.addOrUpdateService(LONG_SERVICE_ID_2, LONG_ALL_NETWORKS_SERVICE,
-                DEFAULT_ADVERTISING_OPTION) }
+                DEFAULT_ADVERTISING_OPTION, TEST_CLIENT_UID_1) }
 
         postSync { advertiser.addOrUpdateService(CASE_INSENSITIVE_TEST_SERVICE_ID,
-                ALL_NETWORKS_SERVICE_2, DEFAULT_ADVERTISING_OPTION) }
+                ALL_NETWORKS_SERVICE_2, DEFAULT_ADVERTISING_OPTION, TEST_CLIENT_UID_1) }
 
         // Callbacks for matching network and all networks both get the socket
         postSync {
@@ -508,7 +523,7 @@
                 MdnsAdvertiser(thread.looper, socketProvider, cb, mockDeps, sharedlog, flags,
                     context)
         postSync { advertiser.addOrUpdateService(SERVICE_ID_1, ALL_NETWORKS_SERVICE,
-                DEFAULT_ADVERTISING_OPTION) }
+                DEFAULT_ADVERTISING_OPTION, TEST_CLIENT_UID_1) }
 
         val socketCbCaptor = ArgumentCaptor.forClass(SocketCallback::class.java)
         verify(socketProvider).requestSocket(eq(null), socketCbCaptor.capture())
@@ -523,16 +538,17 @@
 
         // Update with serviceId that is not registered yet should fail
         postSync { advertiser.addOrUpdateService(SERVICE_ID_2, ALL_NETWORKS_SERVICE_SUBTYPE,
-                updateOptions) }
+                updateOptions, TEST_CLIENT_UID_1) }
         verify(cb).onRegisterServiceFailed(SERVICE_ID_2, NsdManager.FAILURE_INTERNAL_ERROR)
 
         // Update service with different NsdServiceInfo should fail
-        postSync { advertiser.addOrUpdateService(SERVICE_ID_1, SERVICE_1_SUBTYPE, updateOptions) }
+        postSync { advertiser.addOrUpdateService(SERVICE_ID_1, SERVICE_1_SUBTYPE, updateOptions,
+                TEST_CLIENT_UID_1) }
         verify(cb).onRegisterServiceFailed(SERVICE_ID_1, NsdManager.FAILURE_INTERNAL_ERROR)
 
         // Update service with same NsdServiceInfo but different subType should succeed
         postSync { advertiser.addOrUpdateService(SERVICE_ID_1, ALL_NETWORKS_SERVICE_SUBTYPE,
-                updateOptions) }
+                updateOptions, TEST_CLIENT_UID_1) }
         verify(mockInterfaceAdvertiser1).updateService(eq(SERVICE_ID_1), eq(setOf(TEST_SUBTYPE)))
 
         // Newly created MdnsInterfaceAdvertiser will get addService() call.
@@ -547,7 +563,7 @@
             MdnsAdvertiser(thread.looper, socketProvider, cb, mockDeps, sharedlog, flags, context)
         verify(mockDeps, times(1)).generateHostname()
         postSync { advertiser.addOrUpdateService(SERVICE_ID_1, SERVICE_1,
-                DEFAULT_ADVERTISING_OPTION) }
+                DEFAULT_ADVERTISING_OPTION, TEST_CLIENT_UID_1) }
         postSync { advertiser.removeService(SERVICE_ID_1) }
         verify(mockDeps, times(2)).generateHostname()
     }
diff --git a/tests/unit/java/com/android/server/connectivity/mdns/MdnsInterfaceAdvertiserTest.kt b/tests/unit/java/com/android/server/connectivity/mdns/MdnsInterfaceAdvertiserTest.kt
index 0e5cc50..0637ad1 100644
--- a/tests/unit/java/com/android/server/connectivity/mdns/MdnsInterfaceAdvertiserTest.kt
+++ b/tests/unit/java/com/android/server/connectivity/mdns/MdnsInterfaceAdvertiserTest.kt
@@ -18,6 +18,7 @@
 
 import android.net.InetAddresses.parseNumericAddress
 import android.net.LinkAddress
+import android.net.nsd.NsdManager
 import android.net.nsd.NsdServiceInfo
 import android.os.Build
 import android.os.HandlerThread
@@ -26,6 +27,7 @@
 import com.android.server.connectivity.mdns.MdnsAnnouncer.AnnouncementInfo
 import com.android.server.connectivity.mdns.MdnsAnnouncer.BaseAnnouncementInfo
 import com.android.server.connectivity.mdns.MdnsAnnouncer.ExitAnnouncementInfo
+import com.android.server.connectivity.mdns.MdnsInterfaceAdvertiser.CONFLICT_SERVICE
 import com.android.server.connectivity.mdns.MdnsInterfaceAdvertiser.EXIT_ANNOUNCEMENT_DELAY_MS
 import com.android.server.connectivity.mdns.MdnsPacketRepeater.PacketRepeaterCallback
 import com.android.server.connectivity.mdns.MdnsProber.ProbingInfo
@@ -347,7 +349,8 @@
     @Test
     fun testConflict() {
         addServiceAndFinishProbing(TEST_SERVICE_ID_1, TEST_SERVICE_1)
-        doReturn(setOf(TEST_SERVICE_ID_1)).`when`(repository).getConflictingServices(any())
+        doReturn(mapOf(TEST_SERVICE_ID_1 to CONFLICT_SERVICE))
+                .`when`(repository).getConflictingServices(any())
 
         // Reply obtained with:
         // scapy.raw(scapy.DNS(
@@ -373,7 +376,7 @@
         }
 
         thread.waitForIdle(TIMEOUT_MS)
-        verify(cb).onServiceConflict(advertiser, TEST_SERVICE_ID_1)
+        verify(cb).onServiceConflict(advertiser, TEST_SERVICE_ID_1, CONFLICT_SERVICE)
     }
 
     @Test
diff --git a/tests/unit/java/com/android/server/connectivity/mdns/MdnsRecordRepositoryTest.kt b/tests/unit/java/com/android/server/connectivity/mdns/MdnsRecordRepositoryTest.kt
index 06f12fe..fd8d98b 100644
--- a/tests/unit/java/com/android/server/connectivity/mdns/MdnsRecordRepositoryTest.kt
+++ b/tests/unit/java/com/android/server/connectivity/mdns/MdnsRecordRepositoryTest.kt
@@ -22,6 +22,8 @@
 import android.os.Build
 import android.os.HandlerThread
 import com.android.server.connectivity.mdns.MdnsAnnouncer.AnnouncementInfo
+import com.android.server.connectivity.mdns.MdnsInterfaceAdvertiser.CONFLICT_HOST
+import com.android.server.connectivity.mdns.MdnsInterfaceAdvertiser.CONFLICT_SERVICE
 import com.android.server.connectivity.mdns.MdnsRecord.TYPE_A
 import com.android.server.connectivity.mdns.MdnsRecord.TYPE_AAAA
 import com.android.server.connectivity.mdns.MdnsRecord.TYPE_PTR
@@ -52,6 +54,9 @@
 private const val TEST_SERVICE_ID_1 = 42
 private const val TEST_SERVICE_ID_2 = 43
 private const val TEST_SERVICE_ID_3 = 44
+private const val TEST_CUSTOM_HOST_ID_1 = 45
+private const val TEST_CUSTOM_HOST_ID_2 = 46
+private const val TEST_SERVICE_CUSTOM_HOST_ID_1 = 48
 private const val TEST_PORT = 12345
 private const val TEST_SUBTYPE = "_subtype"
 private const val TEST_SUBTYPE2 = "_subtype2"
@@ -86,6 +91,26 @@
     port = TEST_PORT
 }
 
+private val TEST_CUSTOM_HOST_1 = NsdServiceInfo().apply {
+    hostname = "TestHost"
+    hostAddresses = listOf(parseNumericAddress("2001:db8::1"), parseNumericAddress("2001:db8::2"))
+}
+
+private val TEST_CUSTOM_HOST_1_NAME = arrayOf("TestHost", "local")
+
+private val TEST_CUSTOM_HOST_2 = NsdServiceInfo().apply {
+    hostname = "OtherTestHost"
+    hostAddresses = listOf(parseNumericAddress("2001:db8::3"), parseNumericAddress("2001:db8::4"))
+}
+
+private val TEST_SERVICE_CUSTOM_HOST_1 = NsdServiceInfo().apply {
+    hostname = "TestHost"
+    hostAddresses = listOf(parseNumericAddress("2001:db8::1"))
+    serviceType = "_testservice._tcp"
+    serviceName = "TestService"
+    port = TEST_PORT
+}
+
 @RunWith(DevSdkIgnoreRunner::class)
 @DevSdkIgnoreRule.IgnoreUpTo(Build.VERSION_CODES.S_V2)
 class MdnsRecordRepositoryTest {
@@ -569,6 +594,92 @@
             ), reply.additionalAnswers)
     }
 
+
+    @Test
+    fun testGetReply_ptrQuestionForServiceWithCustomHost_customHostUsedInAdditionalAnswers() {
+        val repository = MdnsRecordRepository(thread.looper, deps, TEST_HOSTNAME, makeFlags())
+        repository.initWithService(TEST_SERVICE_CUSTOM_HOST_ID_1, TEST_SERVICE_CUSTOM_HOST_1,
+                setOf(TEST_SUBTYPE, TEST_SUBTYPE2))
+        val src = InetSocketAddress(parseNumericAddress("fe80::1234"), 5353)
+        val serviceName = arrayOf("TestService", "_testservice", "_tcp", "local")
+
+        val query = makeQuery(TYPE_PTR to arrayOf("_testservice", "_tcp", "local"))
+        val reply = repository.getReply(query, src)
+
+        assertNotNull(reply)
+        assertEquals(listOf(
+                MdnsPointerRecord(
+                        arrayOf("_testservice", "_tcp", "local"),
+                        0L, false, LONG_TTL, serviceName)),
+                reply.answers)
+        assertEquals(listOf(
+                MdnsTextRecord(serviceName, 0L, true, LONG_TTL, listOf()),
+                MdnsServiceRecord(serviceName, 0L, true, SHORT_TTL,
+                        0, 0, TEST_PORT, TEST_CUSTOM_HOST_1_NAME),
+                MdnsInetAddressRecord(
+                        TEST_CUSTOM_HOST_1_NAME, 0L, true, SHORT_TTL,
+                        parseNumericAddress("2001:db8::1")),
+                MdnsNsecRecord(serviceName, 0L, true, LONG_TTL, serviceName /* nextDomain */,
+                        intArrayOf(TYPE_TXT, TYPE_SRV)),
+                MdnsNsecRecord(TEST_CUSTOM_HOST_1_NAME, 0L, true, SHORT_TTL,
+                        TEST_CUSTOM_HOST_1_NAME /* nextDomain */,
+                        intArrayOf(TYPE_AAAA)),
+        ), reply.additionalAnswers)
+    }
+
+    @Test
+    fun testGetReply_ptrQuestionForServicesWithSameCustomHost_customHostUsedInAdditionalAnswers() {
+        val repository = MdnsRecordRepository(thread.looper, deps, TEST_HOSTNAME, makeFlags())
+        val serviceWithCustomHost1 = NsdServiceInfo().apply {
+            hostname = "TestHost"
+            hostAddresses = listOf(
+                    parseNumericAddress("2001:db8::1"),
+                    parseNumericAddress("192.0.2.1"))
+            serviceType = "_testservice._tcp"
+            serviceName = "TestService1"
+            port = TEST_PORT
+        }
+        val serviceWithCustomHost2 = NsdServiceInfo().apply {
+            hostname = "TestHost"
+            hostAddresses = listOf(
+                    parseNumericAddress("2001:db8::1"),
+                    parseNumericAddress("2001:db8::3"))
+        }
+        repository.addServiceAndFinishProbing(TEST_SERVICE_ID_1, serviceWithCustomHost1)
+        repository.addServiceAndFinishProbing(TEST_SERVICE_ID_2, serviceWithCustomHost2)
+        val src = InetSocketAddress(parseNumericAddress("fe80::1234"), 5353)
+        val serviceName = arrayOf("TestService1", "_testservice", "_tcp", "local")
+
+        val query = makeQuery(TYPE_PTR to arrayOf("_testservice", "_tcp", "local"))
+        val reply = repository.getReply(query, src)
+
+        assertNotNull(reply)
+        assertEquals(listOf(
+                MdnsPointerRecord(
+                        arrayOf("_testservice", "_tcp", "local"),
+                        0L, false, LONG_TTL, serviceName)),
+                reply.answers)
+        assertEquals(listOf(
+                MdnsTextRecord(serviceName, 0L, true, LONG_TTL, listOf()),
+                MdnsServiceRecord(serviceName, 0L, true, SHORT_TTL,
+                        0, 0, TEST_PORT, TEST_CUSTOM_HOST_1_NAME),
+                MdnsInetAddressRecord(
+                        TEST_CUSTOM_HOST_1_NAME, 0L, true, SHORT_TTL,
+                        parseNumericAddress("2001:db8::1")),
+                MdnsInetAddressRecord(
+                        TEST_CUSTOM_HOST_1_NAME, 0L, true, SHORT_TTL,
+                        parseNumericAddress("192.0.2.1")),
+                MdnsInetAddressRecord(
+                        TEST_CUSTOM_HOST_1_NAME, 0L, true, SHORT_TTL,
+                        parseNumericAddress("2001:db8::3")),
+                MdnsNsecRecord(serviceName, 0L, true, LONG_TTL, serviceName /* nextDomain */,
+                        intArrayOf(TYPE_TXT, TYPE_SRV)),
+                MdnsNsecRecord(TEST_CUSTOM_HOST_1_NAME, 0L, true, SHORT_TTL,
+                        TEST_CUSTOM_HOST_1_NAME /* nextDomain */,
+                        intArrayOf(TYPE_A, TYPE_AAAA)),
+        ), reply.additionalAnswers)
+    }
+
     @Test
     fun testGetReply_singleSubtypePtrQuestion_returnsSrvTxtAddressNsecRecords() {
         val repository = MdnsRecordRepository(thread.looper, deps, TEST_HOSTNAME, makeFlags())
@@ -708,6 +819,90 @@
     }
 
     @Test
+    fun testGetReply_AAAAQuestionForCustomHost_returnsAAAARecords() {
+        val repository = MdnsRecordRepository(thread.looper, deps, TEST_HOSTNAME, makeFlags())
+        repository.initWithService(
+                TEST_CUSTOM_HOST_ID_1, TEST_CUSTOM_HOST_1, subtypes = setOf(),
+                listOf(LinkAddress(parseNumericAddress("192.0.2.111"), 24)))
+        repository.addService(TEST_CUSTOM_HOST_ID_2, TEST_CUSTOM_HOST_2)
+        val src = InetSocketAddress(parseNumericAddress("fe80::123"), 5353)
+
+        val query = makeQuery(TYPE_AAAA to TEST_CUSTOM_HOST_1_NAME)
+        val reply = repository.getReply(query, src)
+
+        assertNotNull(reply)
+        assertEquals(listOf(
+                MdnsInetAddressRecord(TEST_CUSTOM_HOST_1_NAME,
+                        0, false, LONG_TTL, parseNumericAddress("2001:db8::1")),
+                MdnsInetAddressRecord(TEST_CUSTOM_HOST_1_NAME,
+                        0, false, LONG_TTL, parseNumericAddress("2001:db8::2"))),
+                reply.answers)
+        assertEquals(
+                listOf(MdnsNsecRecord(TEST_CUSTOM_HOST_1_NAME,
+                        0L, true, SHORT_TTL,
+                        TEST_CUSTOM_HOST_1_NAME /* nextDomain */,
+                        intArrayOf(TYPE_AAAA))),
+                reply.additionalAnswers)
+    }
+
+
+    @Test
+    fun testGetReply_AAAAQuestionForCustomHostInMultipleRegistrations_returnsAAAARecords() {
+        val repository = MdnsRecordRepository(thread.looper, deps, TEST_HOSTNAME, makeFlags())
+
+        repository.addServiceAndFinishProbing(TEST_CUSTOM_HOST_ID_1, NsdServiceInfo().apply {
+            hostname = "TestHost"
+            hostAddresses = listOf(
+                    parseNumericAddress("2001:db8::1"),
+                    parseNumericAddress("2001:db8::2"))
+        })
+        repository.addServiceAndFinishProbing(TEST_CUSTOM_HOST_ID_2, NsdServiceInfo().apply {
+            hostname = "TestHost"
+            hostAddresses = listOf(
+                    parseNumericAddress("2001:db8::1"),
+                    parseNumericAddress("2001:db8::3"))
+        })
+        val src = InetSocketAddress(parseNumericAddress("fe80::123"), 5353)
+
+        val query = makeQuery(TYPE_AAAA to TEST_CUSTOM_HOST_1_NAME)
+        val reply = repository.getReply(query, src)
+
+        assertNotNull(reply)
+        assertEquals(listOf(
+                MdnsInetAddressRecord(TEST_CUSTOM_HOST_1_NAME,
+                        0, false, LONG_TTL, parseNumericAddress("2001:db8::1")),
+                MdnsInetAddressRecord(TEST_CUSTOM_HOST_1_NAME,
+                        0, false, LONG_TTL, parseNumericAddress("2001:db8::2")),
+                MdnsInetAddressRecord(TEST_CUSTOM_HOST_1_NAME,
+                        0, false, LONG_TTL, parseNumericAddress("2001:db8::3"))),
+                reply.answers)
+        assertEquals(
+                listOf(MdnsNsecRecord(TEST_CUSTOM_HOST_1_NAME,
+                        0L, true, SHORT_TTL,
+                        TEST_CUSTOM_HOST_1_NAME /* nextDomain */,
+                        intArrayOf(TYPE_AAAA))),
+                reply.additionalAnswers)
+    }
+
+    @Test
+    fun testGetReply_customHostRemoved_noAnswerToAAAAQuestion() {
+        val repository = MdnsRecordRepository(thread.looper, deps, TEST_HOSTNAME, makeFlags())
+        repository.initWithService(
+                TEST_CUSTOM_HOST_ID_1, TEST_CUSTOM_HOST_1, subtypes = setOf(),
+                listOf(LinkAddress(parseNumericAddress("192.0.2.111"), 24)))
+        repository.addService(TEST_SERVICE_CUSTOM_HOST_ID_1, TEST_SERVICE_CUSTOM_HOST_1)
+        repository.removeService(TEST_CUSTOM_HOST_ID_1)
+        repository.removeService(TEST_SERVICE_CUSTOM_HOST_ID_1)
+
+        val src = InetSocketAddress(parseNumericAddress("fe80::123"), 5353)
+
+        val query = makeQuery(TYPE_AAAA to TEST_CUSTOM_HOST_1_NAME)
+        val reply = repository.getReply(query, src)
+
+        assertNull(reply)
+    }
+
+    @Test
     fun testGetReply_ptrAndSrvQuestions_doesNotReturnSrvRecordInAdditionalAnswerSection() {
         val repository = MdnsRecordRepository(thread.looper, deps, TEST_HOSTNAME, makeFlags())
         repository.initWithService(TEST_SERVICE_ID_1, TEST_SERVICE_1, setOf(TEST_SUBTYPE))
@@ -815,7 +1010,10 @@
                 emptyList() /* authorityRecords */,
                 emptyList() /* additionalRecords */)
 
-        assertEquals(setOf(TEST_SERVICE_ID_1, TEST_SERVICE_ID_2),
+        assertEquals(
+                mapOf(
+                        TEST_SERVICE_ID_1 to CONFLICT_SERVICE,
+                        TEST_SERVICE_ID_2 to CONFLICT_SERVICE),
                 repository.getConflictingServices(packet))
     }
 
@@ -843,8 +1041,131 @@
             emptyList() /* authorityRecords */,
             emptyList() /* additionalRecords */)
 
-        assertEquals(setOf(TEST_SERVICE_ID_1, TEST_SERVICE_ID_2),
-            repository.getConflictingServices(packet))
+        assertEquals(
+                mapOf(TEST_SERVICE_ID_1 to CONFLICT_SERVICE,
+                        TEST_SERVICE_ID_2 to CONFLICT_SERVICE),
+                repository.getConflictingServices(packet))
+    }
+
+    @Test
+    fun testGetConflictingServices_customHosts_differentAddresses() {
+        val repository = MdnsRecordRepository(thread.looper, deps, TEST_HOSTNAME, makeFlags())
+        repository.addService(TEST_CUSTOM_HOST_ID_1, TEST_CUSTOM_HOST_1)
+        repository.addService(TEST_CUSTOM_HOST_ID_2, TEST_CUSTOM_HOST_2)
+
+        val packet = MdnsPacket(
+                0, /* flags */
+                emptyList(), /* questions */
+                listOf(
+                        MdnsInetAddressRecord(arrayOf("TestHost", "local"),
+                                0L /* receiptTimeMillis */, true /* cacheFlush */,
+                                0L /* ttlMillis */, parseNumericAddress("2001:db8::5")),
+                        MdnsInetAddressRecord(arrayOf("TestHost", "local"),
+                                0L /* receiptTimeMillis */, true /* cacheFlush */,
+                                0L /* ttlMillis */, parseNumericAddress("2001:db8::6")),
+                ) /* answers */,
+                emptyList() /* authorityRecords */,
+                emptyList() /* additionalRecords */)
+
+        assertEquals(mapOf(TEST_CUSTOM_HOST_ID_1 to CONFLICT_HOST),
+                repository.getConflictingServices(packet))
+    }
+
+    @Test
+    fun testGetConflictingServices_customHosts_moreAddressesThanUs_conflict() {
+        val repository = MdnsRecordRepository(thread.looper, deps, TEST_HOSTNAME, makeFlags())
+        repository.addService(TEST_CUSTOM_HOST_ID_1, TEST_CUSTOM_HOST_1)
+        repository.addService(TEST_CUSTOM_HOST_ID_2, TEST_CUSTOM_HOST_2)
+
+        val packet = MdnsPacket(
+                0, /* flags */
+                emptyList(), /* questions */
+                listOf(
+                        MdnsInetAddressRecord(arrayOf("TestHost", "local"),
+                                0L /* receiptTimeMillis */, true /* cacheFlush */,
+                                0L /* ttlMillis */, parseNumericAddress("2001:db8::1")),
+                        MdnsInetAddressRecord(arrayOf("TestHost", "local"),
+                                0L /* receiptTimeMillis */, true /* cacheFlush */,
+                                0L /* ttlMillis */, parseNumericAddress("2001:db8::2")),
+                        MdnsInetAddressRecord(arrayOf("TestHost", "local"),
+                                0L /* receiptTimeMillis */, true /* cacheFlush */,
+                                0L /* ttlMillis */, parseNumericAddress("2001:db8::3")),
+                ) /* answers */,
+                emptyList() /* authorityRecords */,
+                emptyList() /* additionalRecords */)
+
+        assertEquals(mapOf(TEST_CUSTOM_HOST_ID_1 to CONFLICT_HOST),
+                repository.getConflictingServices(packet))
+    }
+
+    @Test
+    fun testGetConflictingServices_customHostsReplyHasFewerAddressesThanUs_noConflict() {
+        val repository = MdnsRecordRepository(thread.looper, deps, TEST_HOSTNAME, makeFlags())
+        repository.addService(TEST_CUSTOM_HOST_ID_1, TEST_CUSTOM_HOST_1)
+        repository.addService(TEST_CUSTOM_HOST_ID_2, TEST_CUSTOM_HOST_2)
+
+        val packet = MdnsPacket(
+                0, /* flags */
+                emptyList(), /* questions */
+                listOf(
+                        MdnsInetAddressRecord(arrayOf("TestHost", "local"),
+                                0L /* receiptTimeMillis */, true /* cacheFlush */,
+                                0L /* ttlMillis */, parseNumericAddress("2001:db8::2")),
+                ) /* answers */,
+                emptyList() /* authorityRecords */,
+                emptyList() /* additionalRecords */)
+
+        assertEquals(emptyMap(),
+                repository.getConflictingServices(packet))
+    }
+
+    @Test
+    fun testGetConflictingServices_customHostsReplyHasIdenticalHosts_noConflict() {
+        val repository = MdnsRecordRepository(thread.looper, deps, TEST_HOSTNAME, makeFlags())
+        repository.addService(TEST_CUSTOM_HOST_ID_1, TEST_CUSTOM_HOST_1)
+        repository.addService(TEST_CUSTOM_HOST_ID_2, TEST_CUSTOM_HOST_2)
+
+        val packet = MdnsPacket(
+                0, /* flags */
+                emptyList(), /* questions */
+                listOf(
+                        MdnsInetAddressRecord(arrayOf("TestHost", "local"),
+                                0L /* receiptTimeMillis */, true /* cacheFlush */,
+                                0L /* ttlMillis */, parseNumericAddress("2001:db8::1")),
+                        MdnsInetAddressRecord(arrayOf("TestHost", "local"),
+                                0L /* receiptTimeMillis */, true /* cacheFlush */,
+                                0L /* ttlMillis */, parseNumericAddress("2001:db8::2")),
+                ) /* answers */,
+                emptyList() /* authorityRecords */,
+                emptyList() /* additionalRecords */)
+
+        assertEquals(emptyMap(),
+                repository.getConflictingServices(packet))
+    }
+
+
+    @Test
+    fun testGetConflictingServices_customHostsCaseInsensitiveReplyHasIdenticalHosts_noConflict() {
+        val repository = MdnsRecordRepository(thread.looper, deps, TEST_HOSTNAME, makeFlags())
+        repository.addService(TEST_CUSTOM_HOST_ID_1, TEST_CUSTOM_HOST_1)
+        repository.addService(TEST_CUSTOM_HOST_ID_2, TEST_CUSTOM_HOST_2)
+
+        val packet = MdnsPacket(
+                0, /* flags */
+                emptyList(), /* questions */
+                listOf(
+                        MdnsInetAddressRecord(arrayOf("TESTHOST", "local"),
+                                0L /* receiptTimeMillis */, true /* cacheFlush */,
+                                0L /* ttlMillis */, parseNumericAddress("2001:db8::1")),
+                        MdnsInetAddressRecord(arrayOf("testhost", "local"),
+                                0L /* receiptTimeMillis */, true /* cacheFlush */,
+                                0L /* ttlMillis */, parseNumericAddress("2001:db8::2")),
+                ) /* answers */,
+                emptyList() /* authorityRecords */,
+                emptyList() /* additionalRecords */)
+
+        assertEquals(emptyMap(),
+                repository.getConflictingServices(packet))
     }
 
     @Test
@@ -873,7 +1194,7 @@
                 emptyList() /* additionalRecords */)
 
         // Above records are identical to the actual registrations: no conflict
-        assertEquals(emptySet(), repository.getConflictingServices(packet))
+        assertEquals(emptyMap(), repository.getConflictingServices(packet))
     }
 
     @Test
@@ -902,7 +1223,7 @@
                 emptyList() /* additionalRecords */)
 
         // Above records are identical to the actual registrations: no conflict
-        assertEquals(emptySet(), repository.getConflictingServices(packet))
+        assertEquals(emptyMap(), repository.getConflictingServices(packet))
     }
 
     @Test