Problem with NSLOOKUP

Josh Littlefield joshl at cisco.com
Fri Jun 4 18:00:25 UTC 1999


I strongly agree that dig is far more useful for DNS debugging than nslookup
for all the reasons you suggested.  But in the PTR example you gave, you
should know that (recent) dig will allow you to specify an in-addr.arpa
lookup more easily, but still explicitly:

  dig -x 199.191.128.103

performs a query of type ANY for 103.128.191.199.in-addr.arpa.

  dig -x 199.191.128.103 ptr

performs a query of type PTR for the same name.

Michael Milligan wrote:
> Strange result.  There is no 199.191.128.103 domain much less a A record
> there.  So, to get what you really wanted (a name from an IP address), you
> have to know to ask for PTR records under the in-addr.arpa domain.  Once you
> know that...
> 
> You type:  dig PTR 103.128.191.199.in-addr.arpa
> You get (something like):
> ---
> ; <<>> DiG 8.2 <<>> PTR 103.128.191.199.in-addr.arpa
> ;; res options: init recurs defnam dnsrch
> ;; got answer:
> ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 6
> ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 4, ADDITIONAL: 4
> ;; QUERY SECTION:
> ;;      103.128.191.199.in-addr.arpa, type = PTR, class = IN
> 
> ;; ANSWER SECTION:
> 103.128.191.199.in-addr.arpa.  23h24s IN PTR  rbru.br.rs.els-gms.att.net.
> 
> ;; AUTHORITY SECTION:
> 128.191.199.in-addr.arpa.  5d23h56m59s IN NS  WYCU.WY.BR.NP.els-gms.att.net.
> 128.191.199.in-addr.arpa.  5d23h56m59s IN NS  OHCU.OH.MT.NP.els-gms.att.net.
> 128.191.199.in-addr.arpa.  5d23h56m59s IN NS  MACU.MA.MT.NP.els-gms.att.net.
> 128.191.199.in-addr.arpa.  5d23h56m59s IN NS  ORCU.OR.BR.NP.els-gms.att.net.
> 
> ;; ADDITIONAL SECTION:
> WYCU.WY.BR.NP.els-gms.att.net.  1d23h56m59s IN A  199.191.128.43
> OHCU.OH.MT.NP.els-gms.att.net.  1d23h56m59s IN A  199.191.144.75
> MACU.MA.MT.NP.els-gms.att.net.  1d23h56m59s IN A  199.191.145.136
> ORCU.OR.BR.NP.els-gms.att.net.  1d23h56m59s IN A  199.191.129.139
> 
> ;; Total query time: 10 msec
> ;; FROM: shadow.acmebw.com to SERVER: default -- 127.0.0.1
> ;; WHEN: Fri Jun  4 03:15:22 1999
> ;; MSG SIZE  sent: 46  rcvd: 271
-- 
========================================================================
Josh Littlefield                                     Cisco Systems, Inc.
joshl at cisco.com                                         250 Apollo Drive
tel: 978-244-8378  fax: 978-244-8378          Chelmsford, MA  01824-3627



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