Re: Missing A records in cache

Hello,

Thanks for the response.

I would think that is what is happening but it is not. Once the A record
disappears from cache, the name becomes unresolveable until the cache is
cleared and repopulated with both the A and NS records. As I mentioned this
only happens with this one site. Any idea why my DNS server would not look
up the A record again?

Thanks,
Chris

"Kevin D. Goodknecht Sr. [MVP]" wrote:

Read inline please.

In news:BF2473E1-A90E-42BF-83D8-1B8A29F9EC78@xxxxxxxxxxxxx,
Chris Ramsay <ChrisRamsay@xxxxxxxxxxxxxxxxxxxxxxxxx> typed:
Hello,

I am having a strange problem with resolving names to one specific
internet domain. On occasion my DNS servers will lose the ability to
resolve the t-systems.at domain. Clearing the cache re-enables the
servers ability to resolve the t-systems.at domain. When I click on
advanced view and look at the cache I see that the t-systems folder
contains the following:

(same as parent folder) - Name Server (NS) - ns1.t-systems.at.
ns1 - Host(A) -
212.31.86.100

On the occasions when I cannot resolve the domain I have noticed that
the cache record for t-systems.at is missing the A record. It only
contains the NS record for ns1.t-systems.at.

My best guess is that without this A record, the ns1.t-systems.at name
server is unresolveable and clearing the cache forces my dns server
to issue a query out to get the t-systems.at information. Thus name
lookups fail until the cache is cleared and the t-systems folder is
repopulated.

Can anyone shed some light on why the cache might be missing this
information. It prevents us from sending email to this domain.

The NS record has a Ttl of 86400 seconds (1 day), while the A record has a
Ttl of only 300 seconds. Even after the Ttl expires on the A record, DNS
will use recursion to resolve the A record, because it knows the name to
look for and start the 300 second countdown again.



--
Best regards,
Kevin D. Goodknecht Sr. [MVP]
Hope This Helps

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