Question on ADDITIONAL SECTION

[Stacey Jonathan Marshall - Solaris Software]

  On 12/30/10 11:12, 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
> ;; QUESTION SECTION:
> ;www.cnn.com.                   IN      A
> ;; ANSWER SECTION:
> www.cnn.com.            133     IN      A       157.166.226.25
> www.cnn.com.            133     IN      A       157.166.226.26
> www.cnn.com.            133     IN      A       157.166.255.18
> www.cnn.com.            133     IN      A       157.166.255.19
> www.cnn.com.            133     IN      A       157.166.224.25
> www.cnn.com.            133     IN      A       157.166.224.26
> ;; Query time: 5 msec
> ;; 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
> ;; QUESTION SECTION:
> ;www.cnn.com.                   IN      A
> ;; ANSWER SECTION:
> www.cnn.com.            150     IN      A       157.166.255.18
> www.cnn.com.            150     IN      A       157.166.255.19
> www.cnn.com.            150     IN      A       157.166.224.25
> www.cnn.com.            150     IN      A       157.166.224.26
> www.cnn.com.            150     IN      A       157.166.226.25
> www.cnn.com.            150     IN      A       157.166.226.26
> ;; AUTHORITY SECTION:
> www.cnn.com.            86400   IN      NS      dmtns07.turner.com.
> www.cnn.com.            86400   IN      NS      dmtns01.turner.com.
> www.cnn.com.            86400   IN      NS      dmtns02.turner.com.
> ;; ADDITIONAL SECTION:
> dmtns01.turner.com.     3608    IN      A       157.166.226.169
> dmtns02.turner.com.     3608    IN      A       157.166.224.169
> dmtns07.turner.com.     3608    IN      A       157.166.255.15
> ;; Query time: 541 msec
> ;; SERVER: 61.144.56.100#53(61.144.56.100)
> ;; WHEN: Thu Dec 30 19:06:58 2010
> ;; MSG SIZE  rcvd: 246
>
> For the two queries above, why the second response has a "ADDITIONAL SECTION" 
> included, but the first doesn't?
> Thanks in advance.
> Regards.
> _______________________________________________
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> bind-users at lists.isc.org
> https://lists.isc.org/mailman/listinfo/bind-users

Because the 2nd response also included Authority Section, the additional data 
are the addresses of the authoritative servers.


-- 
--Stacey