[96265] in North American Network Operators' Group
Re: Hotmail blackholing certain IP ranges ?
daemon@ATHENA.MIT.EDU (Bruce Campbell)
Wed Apr 25 19:49:09 2007
Date: Thu, 26 Apr 2007 09:45:20 +1000 (EST)
From: Bruce Campbell <bc-nanog@vicious.dropbear.id.au>
To: nanog@merit.edu
In-Reply-To: <Pine.SOC.4.62.0704252234370.3468@spruce.eng.gla.ac.uk>
Errors-To: owner-nanog@merit.edu
On Wed, 25 Apr 2007, Chris Edwards wrote:
> Some sites have recently reported problems mailing hotmail due to
> inability to resolve the hotmail MX records. This appears to be due to
> the hotmail DNS servers now blackholing DNS queries where the UDP source
> port was < 1024.
A source port of 53 is permitted through (tested against all listed NSes
from multiple locations). TCP queries are dropped, which is a slight
worry as the 'any hotmail.com' response is sitting a mere 12 bytes short
of the magic 512 byte truncation value.
--==--
Bruce.
