HADOOP-12542. TestDNS fails on Windows after HADOOP-12437. Contributed by Chris Nauroth.

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -1312,6 +1312,8 @@ Release 2.8.0 - UNRELEASED
     HADOOP-12508. delete fails with exception when lease is held on blob.
     (Gaurav Kanade via cnauroth)
 
+    HADOOP-12542. TestDNS fails on Windows after HADOOP-12437. (cnauroth)
+
   OPTIMIZATIONS
 
     HADOOP-12051. ProtobufRpcEngine.invoke() should use Exception.toString()

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/net/TestDNS.java

@@ -30,6 +30,7 @@ import javax.naming.NameNotFoundException;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.apache.hadoop.util.Shell;
 import org.apache.hadoop.util.Time;
 
 import org.junit.Test;
@@ -37,6 +38,7 @@ import org.junit.Test;
 import static org.hamcrest.CoreMatchers.not;
 import static org.hamcrest.core.Is.is;
 import static org.junit.Assert.*;
+import static org.junit.Assume.assumeTrue;
 
 /**
  * Test host name and IP resolution and caching.
@@ -185,13 +187,17 @@ public class TestDNS {
    *
    * This test may fail on some misconfigured test machines that don't have
    * an entry for "localhost" in their hosts file. This entry is correctly
-   * configured out of the box on common Linux distributions, OS X and
-   * Windows.
+   * configured out of the box on common Linux distributions and OS X.
+   *
+   * Windows refuses to resolve 127.0.0.1 to "localhost" despite the presence of
+   * this entry in the hosts file.  We skip the test on Windows to avoid
+   * reporting a spurious failure.
    *
    * @throws Exception
    */
   @Test (timeout=60000)
   public void testLookupWithHostsFallback() throws Exception {
+    assumeTrue(!Shell.WINDOWS);
     final String oldHostname = changeDnsCachedHostname(DUMMY_HOSTNAME);
 
     try {
@@ -231,7 +237,7 @@ public class TestDNS {
 
   private String getLoopbackInterface() throws SocketException {
     return NetworkInterface.getByInetAddress(
-        InetAddress.getLoopbackAddress()).getDisplayName();
+        InetAddress.getLoopbackAddress()).getName();
   }
 
   /**