[149821] in North American Network Operators' Group
Re: Common operational misconceptions
daemon@ATHENA.MIT.EDU (sthaug@nethelp.no)
Thu Feb 16 07:03:21 2012
Date: Thu, 16 Feb 2012 13:01:43 +0100 (CET)
To: marka@isc.org
From: sthaug@nethelp.no
In-Reply-To: <20120216031208.132481D76BD5@drugs.dv.isc.org>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
> If you want to know if your resolver talks IPv6 to the world and
> supports 4096 EDNS UDP messages the following query will tell you.
>
> dig edns-v6-ok.isc.org txt
>
> Similarly for IPv4.
>
> dig edns-v4-ok.isc.org txt
Both PowerDNS recursor 3.3 and Nominum CNS 3.0.5 have problems
with these queries. They both get the TC answer from 149.20.64.58 /
2001:4f8:0:2::8. Then:
- CNS tries with 4000 EDNS UDP size (4000 is the CNS documented max
UDP size), gets another TC.
- PowerDNS doesn't try to used EDNS at all.
Then they both try TCP and get a RST. And then they return SERVFAIL.
Steinar Haug, Nethelp consulting, sthaug@nethelp.no
