FW: Periodic lookup failures

[Mark Andrews]

> Dear bind experts,
>  
> For a month or so now we've been having an intermittent problem whereby
> one of our DNS servers (not always the same one) will fail to resolve
> external addresses. We've tried using both forwarders and having a
> db.cache file so the root servers are queried and it's made no
> difference. When the problem occurs the lookups timeout.
>  
> Initially we were using bind 8.3.4 but I tried upgrading to 8.4.6 in
> case it was some kind of bug. This is running on Solaris 8.
>  
> On the face of it the problem appears to be a DNS cache issue as when
> named is restarted, everything springs back to life. Also, one time when
> we were investigating the problem, the cache cleanup routine ran and DNS
> started working again. However, when I snooped the network interface
> during the problem, queries appeared to be sent out but I couldn't see
> any reply packets. All very strange.

	Sounds like you are behind a Linux NAT box that has stop forwarding
	replies.  Restarting named gets a different query port.
  
> I've been trying to think what the problem may be, an invalid entry in
> the cache perhaps? I was also wondering whether it may be some kind of
> memory issue although there's always plenty of free memory.
>  
> Anyway, if anyone has any suggestions, they would be most welcome.
>  
> Thanks
>  
> Tony 
> 
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Mark Andrews, ISC
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PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews at isc.org