[105213] in North American Network Operators' Group
Re: DNS problems to RoadRunner - tcp vs udp
daemon@ATHENA.MIT.EDU (Florian Weimer)
Sun Jun 15 04:15:42 2008
From: Florian Weimer <fw@deneb.enyo.de>
To: Jon.Kibler@aset.com
Date: Sun, 15 Jun 2008 10:12:48 +0200
In-Reply-To: <4852B91F.8090205@aset.com> (Jon Kibler's message of "Fri, 13 Jun
2008 14:14:55 -0400")
Cc: nanog@merit.edu
Errors-To: nanog-bounces@nanog.org
* Jon Kibler:
>>>From what I have read, public DNS servers should support both UDP and
>> TCP queries. TCP queries are often used when a UDP query fails, or if
>> the answer is over a certain length.
>>
>
> UDP is used for queries.
>
> TCP is used for zone transfers.
I've seen such claims countless times. 8-( However, you can perform
zone file transfers over UFP in some cases (using IXFR), and TCP
fallback may happen even if you never respond with packets with the TC
bit set.
