Getting Kerberos Auth header only with Fiddler

I am new to Windows authentication and am facing a weird issue.

I have setup an application with SPNEGO filter library for Java.

All settings as per the documentations have been set.

Now when i open the URL of my application from another machine in the same domain, using any browser, i get a negotiation header as

TlRMTVNTUAABAAAAl4II...

This means that it is an NTLM negotiation request.

if i start fiddler and then try to run the same request for testing, i am getting a kerberos authentication request.

YIIGgwYGKwYBBQUCoIIGdzCCBnOgMDAuBg...

This means that when I am calling using fiddler, the browser is assuming that the system is on same network.

I am unable to figure out why this is happening..??

I need the kerberos ticket even in normal execution.

Server: JBoss 4.3.2 GA

anybody has any idea...??

thanks in advance