BIND 9.2.1 and TCP

zack.nash at amd.com zack.nash at amd.com
Thu Nov 7 01:40:20 UTC 2002


The request is for a single A record, ( nash 3600 IN A 192.168.0.1 ), would this be too large to fit in a UDP packet.  Also we have BIND 8 servers that serve the same information and they do not revert to TCP for these records.  Could this possibly be a misconfiguration on my part, or is there no way to restrict the server to only using udp?
Thanks,
Zack

-----Original Message-----
From: Mark.Andrews at isc.org [mailto:Mark.Andrews at isc.org]
Sent: Wednesday, November 06, 2002 4:25 PM
To: Nash, Zack
Cc: bind-users at isc.org
Subject: Re: BIND 9.2.1 and TCP



> Hello,
> 	I have noticed that my BIND 9.2.1 servers are requesting that my DNS Cl
> ients use TCP rather than UDP to resolve hostnames, for all queries against t
> his server.
> 	My understanding is that UDP is used unless the packet is too large the
> n the server will request a TCP connection from the client.  I have seen this
>  occur for queries of a single A record.  Is this behavior a bug or is this a
>  new standard that is being implemented with the advent of BIND 9?
> Thanks,
> Zack

	Well the answers must be too big to fit in the space available in a
	UDP response.  Remember the authority section can also trigger TC.

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



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