diff --git a/hbase-examples/src/test/java/org/apache/hadoop/hbase/coprocessor/example/TestZooKeeperScanPolicyObserver.java b/hbase-examples/src/test/java/org/apache/hadoop/hbase/coprocessor/example/TestZooKeeperScanPolicyObserver.java
index 23c97dc6748c..98514cb83a4c 100644
--- a/hbase-examples/src/test/java/org/apache/hadoop/hbase/coprocessor/example/TestZooKeeperScanPolicyObserver.java
+++ b/hbase-examples/src/test/java/org/apache/hadoop/hbase/coprocessor/example/TestZooKeeperScanPolicyObserver.java
@@ -66,7 +66,7 @@ public static void setUp() throws Exception {
         .createTable(TableDescriptorBuilder.newBuilder(NAME)
             .setCoprocessor(ZooKeeperScanPolicyObserver.class.getName())
             .setValue(ZooKeeperScanPolicyObserver.ZK_ENSEMBLE_KEY,
-              "localhost:" + UTIL.getZkCluster().getClientPort())
+              UTIL.getZkCluster().getAddress().toString())
             .setValue(ZooKeeperScanPolicyObserver.ZK_SESSION_TIMEOUT_KEY, "2000")
             .setColumnFamily(ColumnFamilyDescriptorBuilder.newBuilder(FAMILY).build()).build());
     TABLE = UTIL.getConnection().getTable(NAME);
diff --git a/hbase-replication/src/test/java/org/apache/hadoop/hbase/replication/TestReplicationStateBasic.java b/hbase-replication/src/test/java/org/apache/hadoop/hbase/replication/TestReplicationStateBasic.java
index 4a2c3cd51707..348271905fcd 100644
--- a/hbase-replication/src/test/java/org/apache/hadoop/hbase/replication/TestReplicationStateBasic.java
+++ b/hbase-replication/src/test/java/org/apache/hadoop/hbase/replication/TestReplicationStateBasic.java
@@ -1,4 +1,4 @@
-/**
+/*
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements.  See the NOTICE file
  * distributed with this work for additional information
@@ -33,6 +33,7 @@
 import org.apache.hadoop.hbase.ServerName;
 import org.apache.hadoop.hbase.replication.ReplicationPeer.PeerState;
 import org.apache.hadoop.hbase.util.Pair;
+import org.apache.hadoop.hbase.zookeeper.MiniZooKeeperCluster;
 import org.apache.hadoop.hbase.zookeeper.ZKConfig;
 import org.apache.zookeeper.KeeperException;
 import org.junit.Test;
@@ -373,7 +374,8 @@ protected void populateQueues() throws ReplicationException {
       }
       // Add peers for the corresponding queues so they are not orphans
       rp.getPeerStorage().addPeer("qId" + i,
-        ReplicationPeerConfig.newBuilder().setClusterKey("localhost:2818:/bogus" + i).build(),
+        ReplicationPeerConfig.newBuilder().
+          setClusterKey(MiniZooKeeperCluster.HOST + ":2818:/bogus" + i).build(),
         true, SyncReplicationState.NONE);
     }
   }
diff --git a/hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestZKConnectionRegistry.java b/hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestZKConnectionRegistry.java
index 0d140ae0ec1c..137cb28573a3 100644
--- a/hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestZKConnectionRegistry.java
+++ b/hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestZKConnectionRegistry.java
@@ -38,6 +38,7 @@
 import org.apache.hadoop.hbase.TableName;
 import org.apache.hadoop.hbase.testclassification.ClientTests;
 import org.apache.hadoop.hbase.testclassification.MediumTests;
+import org.apache.hadoop.hbase.zookeeper.MiniZooKeeperCluster;
 import org.apache.hadoop.hbase.zookeeper.ReadOnlyZKClient;
 import org.junit.AfterClass;
 import org.junit.BeforeClass;
@@ -101,7 +102,7 @@ public void test() throws InterruptedException, ExecutionException, IOException
   public void testIndependentZKConnections() throws IOException {
     try (ReadOnlyZKClient zk1 = REGISTRY.getZKClient()) {
       Configuration otherConf = new Configuration(TEST_UTIL.getConfiguration());
-      otherConf.set(HConstants.ZOOKEEPER_QUORUM, "localhost");
+      otherConf.set(HConstants.ZOOKEEPER_QUORUM, MiniZooKeeperCluster.HOST);
       try (ZKConnectionRegistry otherRegistry = new ZKConnectionRegistry(otherConf)) {
         ReadOnlyZKClient zk2 = otherRegistry.getZKClient();
         assertNotSame("Using a different configuration / quorum should result in different " +
diff --git a/hbase-server/src/test/java/org/apache/hadoop/hbase/replication/TestReplicationProcedureRetry.java b/hbase-server/src/test/java/org/apache/hadoop/hbase/replication/TestReplicationProcedureRetry.java
index e9fcc6634664..0cbb5cf0f417 100644
--- a/hbase-server/src/test/java/org/apache/hadoop/hbase/replication/TestReplicationProcedureRetry.java
+++ b/hbase-server/src/test/java/org/apache/hadoop/hbase/replication/TestReplicationProcedureRetry.java
@@ -25,7 +25,6 @@
 import static org.mockito.ArgumentMatchers.anyString;
 import static org.mockito.Mockito.doAnswer;
 import static org.mockito.Mockito.spy;
-
 import java.io.IOException;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hbase.HBaseClassTestRule;
@@ -78,7 +77,7 @@ private void doTest() throws IOException {
     Admin admin = UTIL.getAdmin();
     String peerId = "1";
     ReplicationPeerConfig peerConfig = ReplicationPeerConfig.newBuilder()
-        .setClusterKey("localhost:" + UTIL.getZkCluster().getClientPort() + ":/hbase2").build();
+        .setClusterKey(UTIL.getZkCluster().getAddress().toString() + ":/hbase2").build();
     admin.addReplicationPeer(peerId, peerConfig, true);
 
     assertEquals(peerConfig.getClusterKey(),
diff --git a/hbase-server/src/test/java/org/apache/hadoop/hbase/replication/regionserver/TestReplicationSourceManager.java b/hbase-server/src/test/java/org/apache/hadoop/hbase/replication/regionserver/TestReplicationSourceManager.java
index 79ca400ac4eb..61c3cfefd83a 100644
--- a/hbase-server/src/test/java/org/apache/hadoop/hbase/replication/regionserver/TestReplicationSourceManager.java
+++ b/hbase-server/src/test/java/org/apache/hadoop/hbase/replication/regionserver/TestReplicationSourceManager.java
@@ -1,4 +1,4 @@
-/**
+/*
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements.  See the NOTICE file
  * distributed with this work for additional information
@@ -24,7 +24,6 @@
 import static org.junit.Assert.assertTrue;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
-
 import java.io.IOException;
 import java.lang.reflect.Field;
 import java.net.URLEncoder;
@@ -101,10 +100,8 @@
 import org.junit.rules.TestName;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
-
 import org.apache.hbase.thirdparty.com.google.common.collect.Sets;
 import org.apache.hbase.thirdparty.com.google.protobuf.UnsafeByteOperations;
-
 import org.apache.hadoop.hbase.shaded.protobuf.ProtobufUtil;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.WALProtos;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.WALProtos.BulkLoadDescriptor;
@@ -502,7 +499,7 @@ public void testPeerRemovalCleanup() throws Exception{
     String replicationSourceImplName = conf.get("replication.replicationsource.implementation");
     final String peerId = "FakePeer";
     final ReplicationPeerConfig peerConfig = ReplicationPeerConfig.newBuilder()
-      .setClusterKey("localhost:" + utility.getZkCluster().getClientPort() + ":/hbase").build();
+      .setClusterKey(utility.getZkCluster().getAddress().toString() + ":/hbase").build();
     try {
       DummyServer server = new DummyServer();
       ReplicationQueueStorage rq = ReplicationStorageFactory
@@ -557,7 +554,7 @@ private static long getSizeOfLatestPath() {
   public void testRemovePeerMetricsCleanup() throws Exception {
     final String peerId = "DummyPeer";
     final ReplicationPeerConfig peerConfig = ReplicationPeerConfig.newBuilder()
-      .setClusterKey("localhost:" + utility.getZkCluster().getClientPort() + ":/hbase").build();
+      .setClusterKey(utility.getZkCluster().getAddress().toString() + ":/hbase").build();
     try {
       MetricsReplicationSourceSource globalSource = getGlobalSource();
       final int globalLogQueueSizeInitial = globalSource.getSizeOfLogQueue();
@@ -700,8 +697,6 @@ private static void waitPeer(final String peerId,
 
   /**
    * Remove a peer and wait for it to get cleaned up
-   * @param peerId
-   * @throws Exception
    */
   private void removePeerAndWait(final String peerId) throws Exception {
     final ReplicationPeers rp = manager.getReplicationPeers();
diff --git a/hbase-server/src/test/java/org/apache/hadoop/hbase/tool/TestCanaryTool.java b/hbase-server/src/test/java/org/apache/hadoop/hbase/tool/TestCanaryTool.java
index cdc183e0e28c..f8ef9fa739ff 100644
--- a/hbase-server/src/test/java/org/apache/hadoop/hbase/tool/TestCanaryTool.java
+++ b/hbase-server/src/test/java/org/apache/hadoop/hbase/tool/TestCanaryTool.java
@@ -1,4 +1,4 @@
-/**
+/*
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements.  See the NOTICE file
  * distributed with this work for additional information
@@ -31,7 +31,6 @@
 import static org.mockito.Mockito.spy;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
-
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.ExecutorService;
@@ -62,7 +61,6 @@
 import org.mockito.ArgumentMatcher;
 import org.mockito.Mock;
 import org.mockito.runners.MockitoJUnitRunner;
-
 import org.apache.hbase.thirdparty.com.google.common.collect.Iterables;
 
 @RunWith(MockitoJUnitRunner.class)
@@ -104,7 +102,8 @@ public void testBasicZookeeperCanaryWorks() throws Exception {
 
   @Test
   public void testZookeeperCanaryPermittedFailuresArgumentWorks() throws Exception {
-    final String[] args = { "-t", "10000", "-zookeeper", "-treatFailureAsError", "-permittedZookeeperFailures", "1" };
+    final String[] args = { "-t", "10000", "-zookeeper", "-treatFailureAsError",
+      "-permittedZookeeperFailures", "1" };
     testZookeeperCanaryWithArgs(args);
   }
 
@@ -211,8 +210,10 @@ public void testReadTableTimeouts() throws Exception {
     assertEquals(0, ToolRunner.run(testingUtility.getConfiguration(), canary, args));
     verify(sink, times(tableNames.length)).initializeAndGetReadLatencyForTable(isA(String.class));
     for (int i=0; i<2; i++) {
-      assertNotEquals("verify non-null read latency", null, sink.getReadLatencyMap().get(tableNames[i].getNameAsString()));
-      assertNotEquals("verify non-zero read latency", 0L, sink.getReadLatencyMap().get(tableNames[i].getNameAsString()));
+      assertNotEquals("verify non-null read latency", null,
+        sink.getReadLatencyMap().get(tableNames[i].getNameAsString()));
+      assertNotEquals("verify non-zero read latency", 0L,
+        sink.getReadLatencyMap().get(tableNames[i].getNameAsString()));
     }
     // One table's timeout is set for 0 ms and thus, should lead to an error.
     verify(mockAppender, times(1)).doAppend(argThat(new ArgumentMatcher<LoggingEvent>() {
@@ -309,7 +310,8 @@ private void runRegionserverCanary() throws Exception {
   private void testZookeeperCanaryWithArgs(String[] args) throws Exception {
     Integer port =
       Iterables.getOnlyElement(testingUtility.getZkCluster().getClientPortList(), null);
-    testingUtility.getConfiguration().set(HConstants.ZOOKEEPER_QUORUM, "localhost:" + port);
+    String hostPort = testingUtility.getZkCluster().getAddress().toString();
+    testingUtility.getConfiguration().set(HConstants.ZOOKEEPER_QUORUM, hostPort);
     ExecutorService executor = new ScheduledThreadPoolExecutor(2);
     CanaryTool.ZookeeperStdOutSink sink = spy(new CanaryTool.ZookeeperStdOutSink());
     CanaryTool canary = new CanaryTool(executor, sink);
@@ -317,7 +319,6 @@ private void testZookeeperCanaryWithArgs(String[] args) throws Exception {
 
     String baseZnode = testingUtility.getConfiguration()
       .get(HConstants.ZOOKEEPER_ZNODE_PARENT, HConstants.DEFAULT_ZOOKEEPER_ZNODE_PARENT);
-    verify(sink, atLeastOnce())
-      .publishReadTiming(eq(baseZnode), eq("localhost:" + port), anyLong());
+    verify(sink, atLeastOnce()).publishReadTiming(eq(baseZnode), eq(hostPort), anyLong());
   }
 }
diff --git a/hbase-shell/src/test/ruby/hbase/replication_admin_test.rb b/hbase-shell/src/test/ruby/hbase/replication_admin_test.rb
index 3a3c44745178..c669c2a4212b 100644
--- a/hbase-shell/src/test/ruby/hbase/replication_admin_test.rb
+++ b/hbase-shell/src/test/ruby/hbase/replication_admin_test.rb
@@ -598,7 +598,7 @@ def assert_tablecfs_equal(table_cfs, table_cfs_map)
     end
 
     define_test "set_peer_bandwidth: works with peer bandwidth upper limit" do
-      cluster_key = "localhost:2181:/hbase-test"
+      cluster_key = org.apache.hadoop.hbase.zookeeper.MiniZooKeeperCluster::HOST + ":2181:/hbase-test"
       args = { CLUSTER_KEY => cluster_key }
       command(:add_peer, @peer_id, args)
 
@@ -644,7 +644,7 @@ def assert_tablecfs_equal(table_cfs, table_cfs_map)
     end
 
     define_test "get_peer_config: works with simple clusterKey peer" do
-      cluster_key = "localhost:2181:/hbase-test"
+      cluster_key = org.apache.hadoop.hbase.zookeeper.MiniZooKeeperCluster::HOST + ":2181:/hbase-test"
       args = { CLUSTER_KEY => cluster_key }
       command(:add_peer, @peer_id, args)
       peer_config = command(:get_peer_config, @peer_id)
@@ -654,7 +654,7 @@ def assert_tablecfs_equal(table_cfs, table_cfs_map)
     end
 
     define_test "get_peer_config: works with replicationendpointimpl peer and config params" do
-      cluster_key = 'localhost:2181:/hbase-test'
+      cluster_key = org.apache.hadoop.hbase.zookeeper.MiniZooKeeperCluster::HOST + ":2181:/hbase-test"
       repl_impl = 'org.apache.hadoop.hbase.replication.DummyReplicationEndpoint'
       config_params = { "config1" => "value1", "config2" => "value2" }
       args = { CLUSTER_KEY => cluster_key, ENDPOINT_CLASSNAME => repl_impl,
@@ -670,7 +670,7 @@ def assert_tablecfs_equal(table_cfs, table_cfs_map)
     end
 
     define_test "list_peer_configs: returns all peers' ReplicationPeerConfig objects" do
-      cluster_key = "localhost:2181:/hbase-test"
+      cluster_key = org.apache.hadoop.hbase.zookeeper.MiniZooKeeperCluster::HOST + ":2181:/hbase-test"
       args = { CLUSTER_KEY => cluster_key }
       peer_id_second = '2'
       command(:add_peer, @peer_id, args)
diff --git a/hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/MiniZooKeeperCluster.java b/hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/MiniZooKeeperCluster.java
index 4ec079e15a5e..3a8f9d30a555 100644
--- a/hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/MiniZooKeeperCluster.java
+++ b/hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/MiniZooKeeperCluster.java
@@ -25,12 +25,14 @@
 import java.io.StringWriter;
 import java.net.BindException;
 import java.net.ConnectException;
+import java.net.InetAddress;
 import java.net.InetSocketAddress;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Random;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hbase.HConstants;
+import org.apache.hadoop.hbase.net.Address;
 import org.apache.hadoop.hbase.util.Bytes;
 import org.apache.hadoop.hbase.util.Threads;
 import org.apache.yetus.audience.InterfaceAudience;
@@ -49,12 +51,13 @@
 @InterfaceAudience.Public
 public class MiniZooKeeperCluster {
   private static final Logger LOG = LoggerFactory.getLogger(MiniZooKeeperCluster.class);
-
   private static final int TICK_TIME = 2000;
   private static final int TIMEOUT = 1000;
   private static final int DEFAULT_CONNECTION_TIMEOUT = 30000;
   private static final byte[] STATIC_BYTES = Bytes.toBytes("stat");
   private final int connectionTimeout;
+  public static final String LOOPBACK_HOST = InetAddress.getLoopbackAddress().getHostName();
+  public static final String HOST = LOOPBACK_HOST;
 
   private boolean started;
 
@@ -236,7 +239,7 @@ public int startup(File baseDir, int numZooKeeperServers)
       while (true) {
         try {
           standaloneServerFactory = new NIOServerCnxnFactory();
-          standaloneServerFactory.configure(new InetSocketAddress(currentClientPort),
+          standaloneServerFactory.configure(new InetSocketAddress(LOOPBACK_HOST, currentClientPort),
             configuration.getInt(HConstants.ZOOKEEPER_MAX_CLIENT_CNXNS,
               HConstants.DEFAULT_ZOOKEEPER_MAX_CLIENT_CNXNS));
         } catch (BindException e) {
@@ -418,7 +421,7 @@ private static boolean waitForServerDown(int port, long timeout) throws IOExcept
     long start = System.currentTimeMillis();
     while (true) {
       try {
-        send4LetterWord("localhost", port, "stat", (int)timeout);
+        send4LetterWord(HOST, port, "stat", (int)timeout);
       } catch (IOException e) {
         return true;
       }
@@ -441,7 +444,7 @@ private static boolean waitForServerUp(int port, long timeout) throws IOExceptio
     long start = System.currentTimeMillis();
     while (true) {
       try {
-        String result = send4LetterWord("localhost", port, "stat", (int)timeout);
+        String result = send4LetterWord(HOST, port, "stat", (int)timeout);
         if (result.startsWith("Zookeeper version:") && !result.contains("READ-ONLY")) {
           return true;
         } else {
@@ -449,10 +452,10 @@ private static boolean waitForServerUp(int port, long timeout) throws IOExceptio
         }
       } catch (ConnectException e) {
         // ignore as this is expected, do not log stacktrace
-        LOG.info("localhost:{} not up: {}", port, e.toString());
+        LOG.info("{}:{} not up: {}", HOST, port, e.toString());
       } catch (IOException e) {
         // ignore as this is expected
-        LOG.info("localhost:{} not up", port, e);
+        LOG.info("{}:{} not up", HOST, port, e);
       }
 
       if (System.currentTimeMillis() > start + timeout) {
@@ -472,6 +475,13 @@ public int getClientPort() {
         : clientPortList.get(activeZKServerIndex);
   }
 
+  /**
+   * @return Address for this  cluster instance.
+   */
+  public Address getAddress() {
+    return Address.fromParts(HOST, getClientPort());
+  }
+
   List<ZooKeeperServer> getZooKeeperServers() {
     return zooKeeperServers;
   }
diff --git a/hbase-zookeeper/src/test/java/org/apache/hadoop/hbase/zookeeper/TestReadOnlyZKClient.java b/hbase-zookeeper/src/test/java/org/apache/hadoop/hbase/zookeeper/TestReadOnlyZKClient.java
index b5b95307b3d5..ca661458fe92 100644
--- a/hbase-zookeeper/src/test/java/org/apache/hadoop/hbase/zookeeper/TestReadOnlyZKClient.java
+++ b/hbase-zookeeper/src/test/java/org/apache/hadoop/hbase/zookeeper/TestReadOnlyZKClient.java
@@ -1,4 +1,4 @@
-/**
+/*
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements.  See the NOTICE file
  * distributed with this work for additional information
@@ -36,7 +36,6 @@
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
-
 import java.io.IOException;
 import java.util.Collections;
 import java.util.List;
@@ -83,8 +82,9 @@ public class TestReadOnlyZKClient {
   @BeforeClass
   public static void setUp() throws Exception {
     final int port = UTIL.startMiniZKCluster().getClientPort();
+    String hostPort = UTIL.getZkCluster().getAddress().toString();
 
-    ZooKeeper zk = ZooKeeperHelper.getConnectedZooKeeper("localhost:" + port, 10000);
+    ZooKeeper zk = ZooKeeperHelper.getConnectedZooKeeper(hostPort, 10000);
     DATA = new byte[10];
     ThreadLocalRandom.current().nextBytes(DATA);
     zk.create(PATH, DATA, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
@@ -93,7 +93,7 @@ public static void setUp() throws Exception {
     }
     zk.close();
     Configuration conf = UTIL.getConfiguration();
-    conf.set(HConstants.ZOOKEEPER_QUORUM, "localhost:" + port);
+    conf.set(HConstants.ZOOKEEPER_QUORUM, hostPort);
     conf.setInt(ReadOnlyZKClient.RECOVERY_RETRY, 3);
     conf.setInt(ReadOnlyZKClient.RECOVERY_RETRY_INTERVAL_MILLIS, 100);
     conf.setInt(ReadOnlyZKClient.KEEPALIVE_MILLIS, 3000);
diff --git a/hbase-zookeeper/src/test/java/org/apache/hadoop/hbase/zookeeper/TestZKMainServer.java b/hbase-zookeeper/src/test/java/org/apache/hadoop/hbase/zookeeper/TestZKMainServer.java
index 264baad277a4..0fda614e6245 100644
--- a/hbase-zookeeper/src/test/java/org/apache/hadoop/hbase/zookeeper/TestZKMainServer.java
+++ b/hbase-zookeeper/src/test/java/org/apache/hadoop/hbase/zookeeper/TestZKMainServer.java
@@ -19,7 +19,6 @@
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
-
 import java.security.Permission;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hbase.HBaseClassTestRule;
@@ -84,8 +83,8 @@ public void testCommandLineWorks() throws Exception {
       ZKUtil.checkExists(zkw, znode);
       boolean exception = false;
       try {
-        ZKMainServer.main(new String [] {"-server",
-          "localhost:" + htu.getZkCluster().getClientPort(), "delete", znode});
+        ZKMainServer.main(new String [] {"-server", htu.getZkCluster().getAddress().toString(),
+          "delete", znode});
       } catch (ExitException ee) {
         // ZKMS calls System.exit which should trigger this exception.
         exception = true;