Question on ADDITIONAL SECTION

[David Sparro]

On 12/30/2010 6:12 AM, pyh at mail.nsbeta.info wrote:
> $ dig www.cnn.com @202.96.128.166
> ; <<>> DiG 9.4.2-P2 <<>> www.cnn.com @202.96.128.166
> ;; global options: printcmd
> ;; Got answer:
> ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 65353
> ;; flags: qr rd ra; QUERY: 1, ANSWER: 6, AUTHORITY: 0, ADDITIONAL: 0
> ;; SERVER: 202.96.128.166#53(202.96.128.166)
> ;; WHEN: Thu Dec 30 19:07:17 2010
> ;; MSG SIZE rcvd: 125
>
> $ dig www.cnn.com @61.144.56.100
> ; <<>> DiG 9.4.2-P2 <<>> www.cnn.com @61.144.56.100
> ;; global options: printcmd
> ;; Got answer:
> ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 10034
> ;; flags: qr rd ra; QUERY: 1, ANSWER: 6, AUTHORITY: 3, ADDITIONAL: 3
 >
> For the two queries above, why the second response has a "ADDITIONAL
> SECTION" included, but the first doesn't?

Because the servers at 202.96.128.166 and 61.144.56.100 are either 
configured differently or they use different DNS server implementations.

See BIND option "minimal-responses"
or
http://cr.yp.to/djbdns/dnscache.html  (Responses to DNS clients section)
etc.

-- 
Dave