Hotmail blackholing certain IP ranges ?

Wed Apr 25 23:45:20 UTC 2007

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.