FW: "no data known" vrs "host not found"

[Barry Margolin]

In article <a8fmi1$rl6 at pub3.rc.vix.com>, bert hubert  <ahu at ds9a.nl> wrote:
>In article <a8f841$pbk at pub3.rc.vix.com>, Barry Margolin wrote:
>> In article <a8dcva$el7 at pub3.rc.vix.com>, bert hubert  <ahu at ds9a.nl> wrote:
>>>In article <a8cnof$big at pub3.rc.vix.com>, Barry Margolin wrote:
>>>
>>>> Once you've performed an MX or A query, your server has information for the
>>>> name cached.  An ANY query will return whatever happens to be in the cache.
>>>
>>>I think that highly unlikely. 
>> 
>> Why?  Isn't that what's specified in the protocol?  Here's what RFC 1034
>> says:
>
>You cite the wrong part - this is regarding zone data for which the
>nameserver is authoritative. RFC 1034 is actually none to clear in this and
>many other respects.
>
>Item 4 & 5 of the algorithm specify caching behaviour:
>
> 4. Start matching down in the cache.  If QNAME is found in the
>      cache, copy all RRs attached to it that match QTYPE into the
>      answer section.  If there was no delegation from
>      authoritative data, look for the best one from the cache, and
>      put it in the authority section.  Go to step 6.
>
>   5. Using the local resolver or a copy of its algorithm (see
>      resolver section of this memo) to answer the query.  Store
>      the results, including any intermediate CNAMEs, in the answer
>      section of the response.

OK, I quoted the wrong part, but the result is the same.  If there are any
records for the name cached, step 4 will be satisfied (because all the
cached records match QTYPE=ANY).  Step 5, which would forward the query (to
the forwarders or authoritative servers, as specified in the server's
configuration), is not executed.

-- 
Barry Margolin, barmar at genuity.net
Genuity, Woburn, MA
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