Different handling of referrals by dig and nslookup

kalpesh varyani kalpesh.link at gmail.com
Sat Feb 13 17:07:03 UTC 2010


Hi all,

I have named 9.4.3-P3 running on 2 linux systems(A & B).
A has recursion disabled and the B has recursion enabled.

>From a third linux system, I try name resolution using dig or nslookup.
In this system, I have resolv.conf as:

nameserver A
nameserver B

When I try to resolve names, using dig (with +notrace) and ping, I observe
that both these utilites, upon getting a referral discontinues the
resolution process.

# dig foo.example.com.

; <<>> DiG 9.3.2 <<>> foo.example.com.
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 1004
;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 13, ADDITIONAL: 0

;; QUESTION SECTION:
;foo.example.com.               IN      A

;; AUTHORITY SECTION:
.                       83311   IN      NS      e.root-servers.net.
.                       83311   IN      NS      f.root-servers.net.
.                       83311   IN      NS      g.root-servers.net.
.                       83311   IN      NS      h.root-servers.net.
.                       83311   IN      NS      i.root-servers.net.
.                       83311   IN      NS      j.root-servers.net.
.                       83311   IN      NS      k.root-servers.net.
.                       83311   IN      NS      l.root-servers.net.
.                       83311   IN      NS      m.root-servers.net.
.                       83311   IN      NS      a.root-servers.net.
.                       83311   IN      NS      b.root-servers.net.
.                       83311   IN      NS      c.root-servers.net.
.                       83311   IN      NS      d.root-servers.net.

;; Query time: 4 msec
;; SERVER: xx.xxx.xxx.xxx#53(xx.xxx.xxx.xxx)
;; WHEN: Sat Feb 13 21:09:39 2010
;; MSG SIZE  rcvd: 244

#


That is, when name server A returns a referral, dig & ping donot try to
query the name server, i.e. B, specified in resolv.conf.

But, when I use nslookup, I see that it whenever it gets a referral, it
queries the next name server specified in resolv.conf.
This is a desired behaviour as nslookup has nofail option as default
(specified in the man page of nslookup).

I would like have "ping" querying the next name sever in the event of
receiving a referral from the first name sever.
Can anyone suggest whether this is feature is really not supported in dig
and ping?

Thanks in advance!

Regards,
Kalpesh.
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