--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/jdk/java/net/InetAddress/ptr/Lookup.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,104 @@
+/*
+ * Copyright (c) 2002, 2016, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * Lookup/reverse lookup class for regression test 4773521
+ * @test
+ * @bug 4773521
+ * @summary Test that reverse lookups of IPv4 addresses work when IPv6
+ *          is enabled
+ * @library /test/lib
+ * @build jdk.test.lib.Utils
+ *        jdk.test.lib.Asserts
+ *        jdk.test.lib.JDKToolFinder
+ *        jdk.test.lib.JDKToolLauncher
+ *        jdk.test.lib.Platform
+ *        jdk.test.lib.process.*
+ *        Lookup
+ * @run main Lookup root
+ *
+ */
+import java.io.IOException;
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+import java.util.List;
+
+import jdk.test.lib.JDKToolFinder;
+import jdk.test.lib.process.OutputAnalyzer;
+
+public class Lookup {
+    private static final String HOST = "icann.org";
+    private static final String SKIP = "SKIP";
+    private static final String CLASS_PATH = System.getProperty(
+            "test.class.path");
+
+    public static void main(String args[]) throws IOException {
+        String addr = null;
+        String ipv4Name = null;
+        if (args.length == 0) {
+            // First check that host resolves to IPv4 address
+            try {
+                InetAddress ia = InetAddress.getByName(HOST);
+                addr = ia.getHostAddress();
+            } catch (UnknownHostException e) {
+                System.out.print(SKIP);
+                return;
+            }
+        } else {
+            String tmp = lookupWithIPv4Prefer();
+            System.out.println("IPv4 lookup results: [" + tmp + "]");
+            if (SKIP.equals(tmp)) {
+                System.out.println(HOST + " can't be resolved - test skipped.");
+                return;
+            }
+
+            String[] strs = tmp.split(":");
+            addr = strs[0];
+            ipv4Name = strs[1];
+        }
+
+        // reverse lookup
+        InetAddress ia = InetAddress.getByName(addr);
+        String name = ia.getHostName();
+        if (args.length == 0) {
+            System.out.print(addr + ":" + name);
+            return;
+        } else {
+            System.out.println("(default) " + addr + "--> " + name);
+            if (!ipv4Name.equals(name)) {
+                throw new RuntimeException("Mismatch between default"
+                        + " and java.net.preferIPv4Stack=true results");
+            }
+        }
+    }
+
+    static String lookupWithIPv4Prefer() throws IOException {
+        String java = JDKToolFinder.getTestJDKTool("java");
+        String testClz = Lookup.class.getName();
+        List<String> cmd = List.of(java, "-Djava.net.preferIPv4Stack=true",
+                "-cp", CLASS_PATH, testClz);
+        System.out.println("Executing: " + cmd);
+        return new OutputAnalyzer(new ProcessBuilder(cmd).start()).getOutput();
+    }
+}
+