FULL PRODUCT VERSION :
# ./java -version
java version "1.6.0_07"

ADDITIONAL OS VERSION INFORMATION :
All OS

A DESCRIPTION OF THE PROBLEM :
For some ip addresses getHostName returns ip address instead of resolving into domain name

eg:
# ./java ipres 137.227.5.37
137.227.5.37

Only on Redhat gcj version of java, getHostName() returns hostname for that ip

# java -version java version "1.4.2"
gcj (GCC) 3.4.6 20060404 (Red Hat 3.4.6-8) Copyright (C) 2006 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

# java ipres 137.229.5.37
rakof-ilo.alaska.edu

I've default java security manager settings.


nslookup is working fine for all ip.

# nslookup 137.229.5.37
Server: 10.206.194.12
Address: 10.206.194.12#53

Non-authoritative answer:
37.5.229.137.in-addr.arpa name = rakof-ilo.alaska.edu.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Run my ipres class

# ./java ipres 137.227.5.37
137.227.5.37


============code==================
import java.net.*;
class ipres
{
public static void main(String[] args)
{
String hostName;
try {
InetAddress address;
address = InetAddress.getByName(args[0]);
hostName = address.getHostName();
System.out.println(hostName);
}
catch (Exception e)

{
System.out.println("Exception");
}

}
}
===========================================


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
should return hostname (rakof-ilo.alaska.edu)
ACTUAL -
-# ./java ipres 137.227.5.37
137.227.5.37



REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
============code==================
import java.net.*;
class ipres
{
public static void main(String[] args)
{
String hostName;
try {
InetAddress address;
address = InetAddress.getByName(args[0]);
hostName = address.getHostName();
System.out.println(hostName);
}
catch (Exception e)

{
System.out.println("Exception");
}

}
}
===========================================
---------- END SOURCE ----------