need help figuring this MX /A record query problem out

[Brad Knowles]

At 7:55 AM -0500 5/17/01, King, John (Greg) (OAO-HOU) wrote:

>  Second test following first. Note that i get only 2 Additional Records
>  instead of 4. Why is this? I think this is where the records are going away.
>  If i stop and start bind i can get the first lookup everytime, any
>  subsequent lookups dont return all the info though.

	This is because the first answer was provided with an 
"Authoritative" flag by the other nameserver, and did not come out of 
cache.  The entire authoritative answer was passed on to your client 
without modification.

	However, the second answer came out of cache, and there the 
nameserver added only the additional glue records to tell you where 
you can find the answer you're looking for, as opposed to including 
the IP addresses of the MXes themselves.  If you did a query of type 
"any" instead of "mx", you might have gotten all four additional 
records in both cases, but you'd need to test that out to be sure.

>  zone "." in {
>          type hint;
>          file "db.cache";
>  };
>
>  zone "0.0.127.in-addr.arpa" in {
>          type master;
>          file "db.127.0.0";
>  };
>
>  zone "some.dom.ain" in {
>          type master;
>          file "db.some.dom.ain";
>          check-names ignore;
>          allow-update { none; };
>          allow-query { any; };
>          allow-transfer { x.x.x.x; };
>          notify no;
>  };

	Note that I am not at all a fan of mixing authoritative with 
caching services on the same nameserver (or, at least, on the same 
instance of BIND).  I believe that you're much better off splitting 
these jobs onto separate machines, so that each can be configured and 
tuned to perform only that one role and do it well, as opposed to 
doing more poorly at trying to serve two roles.

-- 
Brad Knowles, <brad.knowles at skynet.be>

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