suffix for the Host Name which is'nt needed

Hello,

If I do a ping from my pc to the router via

Code:

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ping wl500gp

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I get no answer!

If I do a ping from my pc to the router via

Code:

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ping wl500gp.router

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It works perfectly.

If I do a ping from my router to the router via

Code:

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ping wl500gp

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It works!?!?!

I found out that the suffix comes from the configuration "Domain Name" under IP Config - DHCP Server. If I remove the "Domain Name" I can't send a ping any more to my router!
Is there a way to remove the suffix?

Thanks a lot.