diff --git a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/DatanodeID.java b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/DatanodeID.java
index f162348244021..cd95373e7467b 100644
--- a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/DatanodeID.java
+++ b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/DatanodeID.java
@@ -302,6 +302,7 @@ public void updateRegInfo(DatanodeID nodeReg) {
     setIpAndXferPort(nodeReg.getIpAddr(), nodeReg.getIpAddrBytes(),
         nodeReg.getXferPort());
     hostName = nodeReg.getHostName();
+    hostNameBytes = nodeReg.getHostNameBytes();
     peerHostName = nodeReg.getPeerHostName();
     infoPort = nodeReg.getInfoPort();
     infoSecurePort = nodeReg.getInfoSecurePort();
diff --git a/hadoop-hdfs-project/hadoop-hdfs-client/src/test/java/org/apache/hadoop/hdfs/protocol/TestDatanodeID.java b/hadoop-hdfs-project/hadoop-hdfs-client/src/test/java/org/apache/hadoop/hdfs/protocol/TestDatanodeID.java
new file mode 100644
index 0000000000000..f4022339878f7
--- /dev/null
+++ b/hadoop-hdfs-project/hadoop-hdfs-client/src/test/java/org/apache/hadoop/hdfs/protocol/TestDatanodeID.java
@@ -0,0 +1,39 @@
+/**
+ * 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
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hdfs.protocol;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class TestDatanodeID {
+
+  @Test
+  public void testUpdateRegInfoUpdatesHostNameBytes() {
+    DatanodeID original = new DatanodeID("1.2.3.4", "host1-dc2",
+        "uuid-1", 9866, 9864, 9865, 9867);
+
+    DatanodeID updated = new DatanodeID("1.2.3.4", "host1-dc2.example.com",
+        "uuid-1", 9866, 9864, 9865, 9867);
+
+    original.updateRegInfo(updated);
+    assertEquals("host1-dc2.example.com", original.getHostName());
+    assertEquals("host1-dc2.example.com",
+        original.getHostNameBytes().toStringUtf8());
+  }
+}
\ No newline at end of file