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

[Jon R. Kibler]

Consider the following lame server message:

	Dec  7 17:50:58 asethost named[136]: Lame server on '1.2.151.128.IN-ADDR.ARPA' 
	     (in '151.128.in-addr.arpa'?): [128.151.128.52].53 'NS.UTD.ROCHESTER.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 between A and NS? 

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 authoritative 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 derived, 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.
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