FULL PRODUCT VERSION :
java version "1.6.0-beta"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.6.0-beta-b59g)
Java HotSpot(TM) Client VM (build 1.6.0-beta-b59g, mixed mode, sharing)

also verified for:

java version "1.5.0_06"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_06-b05)
Java HotSpot(TM) Client VM (build 1.5.0_06-b05, mixed mode)


ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows 2000 [Version 5.00.2195]

EXTRA RELEVANT SYSTEM CONFIGURATION :
testes for 1.6.0 beta and 1.5.0_06

A DESCRIPTION OF THE PROBLEM :
InetAddress.getByName(), when provided with a literal v4 ip address, tries a reverse dns lookup, although the documentation states otherwise: "If a literal IP address is supplied, only the validity of the address format is checked."

On windows, this will produce a delay of about 4.5 seconds for this call.

Seems to be related to issue 5092063


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. make sure that a reverse DNS resolution fails for the IP specified in the code below, and/or start an ethereal trace
2. excute the code

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
response time should be faster
ACTUAL -
1.6.0-beta
address=192.168.42.42
4515 ms

and

1.5.0_06
address=192.168.42.42
4500 ms


REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.net.*;

class Test {

public static void main(String args[]) throws Exception {


System.out.println(System.getProperty("java.version"));
long before = System.currentTimeMillis();
InetAddress addr = InetAddress.getByName("192.168.42.42");
System.out.println("address=" + addr.getHostName());
long after = System.currentTimeMillis();
System.out.println((after - before) + " ms");

}
}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
fixing dns reverse lookup, e.g. by putting the ip's as names into the local hosts file, if practical.