North American Network Operators Group|
Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical
Re: Hotmail blackholing certain IP ranges ?
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.