[105163] in North American Network Operators' Group
Re: DNS problems to RoadRunner - tcp vs udp
daemon@ATHENA.MIT.EDU (Mike Lewinski)
Fri Jun 13 14:22:28 2008
Date: Fri, 13 Jun 2008 12:22:07 -0600
From: Mike Lewinski <mike@rockynet.com>
To: nanog@merit.edu
In-Reply-To: <4852B91F.8090205@aset.com>
Errors-To: nanog-bounces@nanog.org
Jon Kibler wrote:
> UDP is used for queries.
>
> TCP is used for zone transfers.
>
> If my server responded to TCP queries from anyone other than a secondary
> server, I would be VERY concerned.
That is a common, but incorrect, assumption.
DNS responses that are larger than the MTU of a single UDP packet are
sent as TCP.
Back in the day (c. 1998) Microsoft had some arpa zones that they felt
it necessary to create hundreds of PTRs per entry. Of course, they
denied TCP to their nameservers. The end result is that our BIND8 server
was crashing on the lookups (it was a crappy port to NT).
