Two RFC2317 Questions

[Andris Kalnozols]

> In article <a921bg$9o1 at pub3.rc.vix.com>, Barry Margolin wrote:
>  
> > Notice that dig defaults to querying for an A record.
> > 
> > When I specify PTR I get the expected result:
> > 
> > % dig -x 216.60.241.0.17 ptr
> > 
> > ; <<>> DiG 8.3 <<>> -x ptr 
> > ;; res options: init recurs defnam dnsrch
> > ;; got answer:
> > ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 4
> > ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 6, ADDITIONAL: 8
> > ;; QUERY SECTION:
> > ;;	17.0.241.60.216.in-addr.arpa, type = PTR, class = IN
> > 
> > ;; ANSWER SECTION:
> > 17.0.241.60.216.in-addr.arpa.  23h59m21s IN PTR  csgax.able.anl.gov.
>
> Will Yardley wrote:
>
> bind9 dig will follow the CNAME:
> (9.3 snapshot doesn't even show the cname, although i think 9.2 dig
> shows both).
> 
> jazz% dig -x 216.60.241.0.17
> 
> ; <<>> DiG 9.3.0s20020328 <<>> -x 216.60.241.0.17
> ;; global options:  printcmd
> ;; Got answer:
> ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 33951
> ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 6, ADDITIONAL: 0
> 
> ;; QUESTION SECTION:
> ;17.0.241.60.216.in-addr.arpa.  IN      PTR
> 
> ;; ANSWER SECTION:
> 17.0.241.60.216.in-addr.arpa. 86400 IN  PTR     csgax.able.anl.gov.
> 
> ;; AUTHORITY SECTION:
> 0.241.60.216.in-addr.arpa. 86400 IN     NS      dns2.anl.gov.
> 0.241.60.216.in-addr.arpa. 86400 IN     NS      ns1.swbell.net.
> 0.241.60.216.in-addr.arpa. 86400 IN     NS      ns2.es.net.
> 0.241.60.216.in-addr.arpa. 86400 IN     NS      ns2.swbell.net.
> 0.241.60.216.in-addr.arpa. 86400 IN     NS      nsx.lbl.gov.
> 0.241.60.216.in-addr.arpa. 86400 IN     NS      dns1.anl.gov.
> 
> ;; Query time: 902 msec
> ;; SERVER: 127.0.0.1#53(127.0.0.1)
> ;; WHEN: Wed Apr 10 19:08:59 2002
> ;; MSG SIZE  rcvd: 205
> 
> -- 

There's no need to resolve the CNAME when directly querying the
RFC2317-delegated domain.  Querying the parent domain does show
the CNAME in the response:

; <<>> DiG 9.2.1rc1 <<>> -x 216.60.241.17 ptr
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 2697
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 6, ADDITIONAL: 9

;; QUESTION SECTION:
;17.241.60.216.in-addr.arpa.    IN      PTR

;; ANSWER SECTION:
17.241.60.216.in-addr.arpa. 5833 IN     CNAME   17.0.241.60.216.in-addr.arpa.
17.0.241.60.216.in-addr.arpa. 84771 IN  PTR     csgax.able.anl.gov.

-----

Andris