The following program demonstrates a problem where Java will not return a hostname. This happens when requests are made using different IP addresses in calls for the (same) hostname (the host has multiple IP addresses).

java.net.*;

public class GetAllByName {
    void doit(String org, InetAddress test) {
        System.out.println("Created by " + org);
        System.out.println("InetAddress.toString() = " + test.toString());
        String name = test.getHostName();
        System.out.println("name = " + name.toString());
        System.out.println("");
    }

    public static void main (String[] args) {
        InetAddress test;
        GetAllByName hn = new GetAllByName();
        String addr = new String("172.29.252.66");
        String addr2 = new String("172.29.252.34");
        String addr3= new String("172.29.252.50");
        String addr4= new String("172.29.252.58");
        String name = new String("sb-4500-1");

        int i;
        InetAddress [] all;

        try {
            all = InetAddress.getAllByName(name);

            System.out.println("getAllByName(" + name + ") found " +
                               all.length + " addresses");
            for (i = 0; i < all.length; ++i) {
                hn.doit(name, all[i]);
            }
        } catch (Exception ex) {
            System.out.println("Caught exception = " + ex);
        }

        try {
            all = InetAddress.getAllByName(addr);

            System.out.println("getAllByName(" + addr + ") found " +
                               all.length + " addresses");

            for (i = 0; i < all.length; ++i) {
                hn.doit(addr, all[i]);
            }
        } catch (Exception ex) {
            System.out.println("Caught exception = " + ex);
        }

        try {
            all = InetAddress.getAllByName(addr2);

            System.out.println("getAllByName(" + addr2 + ") found " +
                               all.length + " addresses");

            for (i = 0; i < all.length; ++i) {
                hn.doit(addr2, all[i]);
            }
        } catch (Exception ex) {
            System.out.println("Caught exception = " + ex);
        }

        try {
            all = InetAddress.getAllByName(addr3);

            System.out.println("getAllByName(" + addr3 + ") found " +
                               all.length + " addresses");

            for (i = 0; i < all.length; ++i) {
                hn.doit(addr3, all[i]);
            }
        } catch (Exception ex) {
            System.out.println("Caught exception = " + ex);
        }

        try {
            all = InetAddress.getAllByName(addr4);

            System.out.println("getAllByName(" + addr4 + ") found " +
                               all.length + " addresses");

            for (i = 0; i < all.length; ++i) {
                hn.doit(addr4, all[i]);
            }
        } catch (Exception ex) {
            System.out.println("Caught exception = " + ex);
        }
    }
}
++++++++++++++++++++++++++++++++++++++++++++++++++++
The results of execution:

Created by sb-4500-1
name = sb-4500-1

Created by 172.29.252.66
name = sb-4500-1.cisco.com

Created by 172.29.252.34
name = 172.29.252.34

Created by 172.29.252.50
name = 172.29.252.50

Created by 172.29.252.58
name = 172.29.252.58

elizabeth.mezias@Eng 1998-11-30