Difference between A= and NS= fields in 'learnt' part of Lame Server message?

[Mark.Andrews at iengines.com]

> Consider the following lame server message:
> 
> 	Dec  7 17:50:58 asethost named[136]: Lame server on '1.2.151.128.IN-ADD
> R.ARPA' 
> 	     (in '151.128.in-addr.arpa'?): [128.151.128.52].53 'NS.UTD.ROCHESTE
> R.EDU': 
> 	     learnt (A=128.105.2.10,NS=128.8.10.90)
> 
> It is clear what is lame, but what isn't clear is how to interpret the learnt
>  part of the message when A= and NS= are different. What is the difference be
> tween A and NS? 

The NS records for 151.128.IN-ADDR.ARPA were learnt from 128.8.10.90.

The A record for NS.UTD.ROCHESTER.EDU (one of the name servers for
151.128.IN-ADDR.ARPA) was learnt from 128.105.2.10.

Both of there are reasonable sources for the relevent records.

Knowing where records were learnt from is often the first step in
eliminating bad data if that was the reason there was a lame response.

Mark

> 
> For example:
> 	nslookup -type=any 151.128.in-addr.arpa. dns.cs.wisc.edu.  (A= case)
> and
> 	nslookup -type=any 151.128.in-addr.arpa. d.root-servers.net.  (NS= case
> )
> 
> return the same results.
> 
> 
> What is even less clear is this example:
> 
> 	Dec 20 06:38:49 asethost named[136]: Lame server on '1.1.1.151.in-addr.
> arpa' 
> 	     (in '1.151.in-addr.arpa'?): [158.43.128.26].53 'NS.PIPEX.NET': 
> 	     learnt (A=128.8.10.90,NS=192.203.230.10)
> 
> where both A and NS are root servers (A=d & ns=e) and both are listed as auth
> oritative for ARPA.
> 
> 
> I looked that the named source code (with its sparse comments) and it was not
>  even remotely clear what the values given for A and NS were, how they were d
> erived, and how they are different.
> 
> Can anyone explain the differences between A and NS?
> 
> THANKS in advance for your help!
> 
> 
> Sincerely,
> Jon R. Kibler
> Systems Architect
> Year 2000 Services Manager
> Jon.Kibler at aset.com
> 
> Advanced Systems Engineering Technology, Inc.
> 389 Johnnie Dodds Blvd., Suite 205
> Mt. Pleasant, SC 29464-2950  (Charleston)
> 
> Phone:	(843) 849-8214
> Fax:	(843) 849-8215
> 
> 
--
Mark Andrews, Internet Engines Inc. / Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark.Andrews at iengines.com