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DNS Query TimeOuts

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hookjd View Drop Down
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    Posted: 20 February 2008 at 12:39pm
Hi there.  For the last few weeks we've been having a lot more spam coming through.  In analyzing the logs I am seeing that there are tons of entries that look like this:

02/20/08 09:29:29:250 -- (2764) DNS Error:TimedOut
02/20/08 09:29:29:250 -- (2764) DNS Server will rotate after query. New server will be 4.2.2.2
At some times it appears that this is happening on almost every query.  I am able to run nslookup and query all the name servers that I have set up with no problem at all.  I've never seen this before, so I'm not sure what could have changed.  I have made one config change where I have moved spamfilter to run on only 1 IP address on that machine, and I have some other email services running on a different IP address.  Any ideas how to troubleshoot this problem?  Its making numerous filters not work correctly and letting way too much spam through.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote LogSat Quote  Post ReplyReply Direct Link To This Post Posted: 20 February 2008 at 10:32pm
The "DNS Error:TimedOut" usually indicates that the DNS server(s) used by SpamFilter are not able to provide timely responses to lookups. The default timeout value is 5 seconds, but we do not recommend increasing it as it may cause emails queues to accumulate as SpamFilter will have to wait longer for each email to be processes while waiting for a DNS result.
What we do recommend is to have SpamFilter use different DNS servers than the ones currently configured, to see if the this improves the DNS lookup performance.
Roberto Franceschetti

LogSat Software

Spam Filter ISP
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hookjd View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote hookjd Quote  Post ReplyReply Direct Link To This Post Posted: 21 February 2008 at 12:56pm
Thanks for your reply.  I was about to post my own response that I discovered from my hosting provider that the Level3 DNS servers we were using were rejecting some queries from my datacenter and that I should change my DNS servers, which I have done.  All seems to be functioning much better now.  I appreciate the help.
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