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DNS Client port range

Posted on 2006-06-25
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Last Modified: 2013-12-04
Hi,

I wish to implement ip filtering on all my client PCs but I'm having problems with my Win2k3 dns server as the client-side port range is massive. To quote MS:

"By default, Windows Server 2003 and Windows 2000 Server DNS servers use ephemeral client-side ports when they query other DNS servers...."

Is there any proper way to reduce the port range on the dns server to a manageable number? Is there a way it can be reduced to a single port? Is there a performance issue with implementing this?

Also, under what conditions does a dns client and server choose to use udp over tcp? Is there any way of choosing just one protocol? Which one is better?

Thanks
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Question by:gibjon
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gidds99 earned 500 total points
ID: 16982632
Windows uses ephemiral ports for DNS connections as you have mentioned above.  These ports fall within the range 1024 to 5000.  You can control this range via a registry setting but it is not only limited to DNS connections (it affects all connections). Clearly if the range was limited too much this may cause problems.

Hope this helps.
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