cache dns server use tcp to query other dns server

Alex Tang alextang at cms.hkcable.com
Fri Jan 6 03:13:43 UTC 2006


that means a client use udp to query my cache dns server and my cache dns server use udp to query other dns server, the other query dns server tell me that the answer is too big and I use tcp to connect other dns server port 53 ? my firewall only allow established tcp connect pass through

is it trun ?

-----Original Message-----
From: Mark_Andrews at isc.org [mailto:Mark_Andrews at isc.org]
Sent: Friday, January 06, 2006 9:52 AM
To: Alex Tang
Cc: bind-users at isc.org
Subject: Re: cache dns server use tcp to query other dns server 



> Hi Everybody
> 
> Would you know why a cache dns server use a lot of tcp connection ( about 10 
> ) to query other dns server ? 
> 
> Please help 
> thx

	Because the answers are too big to fit into a UDP response.

--
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews at isc.org



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