controlling recursion

[Barry Margolin]

In article <dlj81b$1ifv$1 at sf1.isc.org>,
 Jon Leeman <jleeman at cenpac.net.nr> wrote:

> Kevin (with apologies for the direct reply instead of to the list before),
> 
> No I am not / wasn't sure......the test was done by a friend who did;
> 
> dig mx hotmail.com @203.98.224.66 /225.9 /225.10
> 
> and 66 returned

Notice that the TTL is not a round number.  This is usually an 
indication that the answer was already in the cache, so the server 
didn't have to recurse.  And if you query twice and see the TTL drop, 
it's practically certain.

> 
> ; <<>> DiG 9.2.4 <<>> mx hotmail.com @203.98.224.66
> ;; global options:  printcmd
> ;; Got answer:
> ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 56644
> ;; flags: qr rd; QUERY: 1, ANSWER: 4, AUTHORITY: 5, ADDITIONAL: 17
> 
> ;; ANSWER SECTION:
> hotmail.com.   1151    IN      MX      5 mx2.hotmail.com.
> <snip>
> 
> ;; AUTHORITY SECTION:
> hotmail.com.            115430  IN      NS      ns1.msft.net.
> <snip>
> 
> ;; ADDITIONAL SECTION:
> mx1.hotmail.com.        1151    IN      A       64.4.50.99
> <snip>
> 
> while 9 and 10 returned the same except the additional section.
> 
> I'll do some reading on allow-query given your comment re the cache.

-- 
Barry Margolin, barmar at alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***