Off Topic: Caching Bind Server Freezing

[Gottschalk, David]

No firewall blocking going on. Lookups to the local server freeze entirely, I have not checked when this happened if remote looks ups still worked or not. I have to kill named when this occurs as it will not voluntarily restart. I even did a strace on named, and there is no activity.

Doesn't appear to be a lot of network resources in use when it freezes.

David Gottschalk
UTS Email team
david.gottschalk at emory.edu<mailto:david.gottschalk at emory.edu>
404.727.9744

From: mailscanner-bounces at lists.mailscanner.info [mailto:mailscanner-bounces at lists.mailscanner.info] On Behalf Of Landon Stewart
Sent: Wednesday, January 27, 2010 2:31 PM
To: MailScanner discussion
Subject: Re: Off Topic: Caching Bind Server Freezing

On Wed, Jan 27, 2010 at 9:41 AM, Gottschalk, David <dgottsc at emory.edu<mailto:dgottsc at emory.edu>> wrote:
Does anyone here use Bind to cache DNS lookups on their MailScanner boxes?

I have a bind caching server running on each of my MailScanner machines, and occasionally named will completely freeze up. I'm not sure why this is occurring. I thought it might have had to do with SpamHaus lookups hanging (they blocked our lookups), so I disabled them in my mailscanner.cf<http://mailscanner.cf>; however, that has not resolved the issue.

I'm running version 9.2.4.

Hi David,

Are you blocking UDP:53 or TCP:53 with your iptables or upstream?  Do any lookups work at all when its frozen (cached or other)?  Can you perform lookups using other name servers from the machine?  (eg. dig @bitsy.mit.edu<http://bitsy.mit.edu> emory.edu<http://emory.edu>).  When it is frozen what does the output of lsof look like for that process?  Are there a lot of network resources in use by the named process when it freezes?
--
Landon Stewart <LStewart at SUPERB.NET<mailto:LStewart at SUPERB.NET>>
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