To add to what everybody else has said, let me just mention nagios as a potential solution if you don't have a monitoring package already. You can set it up to query specific DNS hosts and AFAIK it is not fooled by cache, unless of course you are querying a cacheing DNS server in the first place! :-D

Where I work we use Netsaint, which is the predecessor to Nagios to keep track of not only the status of our DNS servers but all of our servers across multiple campuses and against a lot of different application types.

One caveat: I have seen failure modes where a bind server can actually be down but pass a cursory DNS check. Make sure whatever check you come up with does a query against a known and unchanging "A" record. For instance I would advise against querying against Yahoo, or Microsoft, or Hotmail since those can change at any time without warning and may result in false triggers. However if my DNS server has a fixed entry in it that I can rely on I write my check to check that one and make sure the answer I get back is what I expected.

Peter L. Berghold -- Unix Professional
Peter -at- Berghold -dot- Net; AOL IM redcowdawg Yahoo IM: blue_cowdawg

In reply to Re: testing a DNS server by blue_cowdawg
in thread testing a DNS server by jimbus

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