nslookup issues on hp-ux

Bill Larson wllarso at swcp.com
Thu Feb 22 15:50:04 UTC 2001


You identified your own answer to your problem.

nslookup in BIND-8 gets linked against the libbind.a and the BIND
resolver libraries.  This is NOT the system libraries!  Any
modification of the system libraries, by yourself or HP, will not get
reflected in the operation of nslookup.

This difference between the resolver library that nslookup uses
compared to the library that is provided by the system CAN cause
differences in operation.  One example is that the BIND nslookup does
not use /etc/nsswitch.conf to determine HOW to resolve names.  On
old Sun systems, I have seen other differences too.

HP uses it's "nslookup" tool extensively in it's SAM, system
administration tool.  Because of this, I would suggest that you do NOT
install the BIND version of nslookup on an HP system.

If you are trying to troubleshoot a DNS problem, a symple solution is
to avoid using nslookup and move to using dig.  dig seems to operate at
a "lower" level of the DNS protocol.  It responds more correctly to DNS
queries, without involving system level resolver issues, such as
/etc/nsswitch.conf.

Bill Larson

> Okay, now I'm really confused. I thought nslookup called resolver
> routines, which are supposed to check /etc/nsswitch.conf. The libbind.a
> looks like it compiles its own versions of the resolver routines, then
> gets linked into nslookup. So it is not using the native resolver routines
> from HP-UX, which, according to the man pages, go to nsswitch.conf to see
> where to resolve from. Also, both texts I consulted ("DNS and BIND, 3rd
> Ed." and "(The Concise Guide to) DNS and BIND") describe this resolver
> behavior, that nslookup uses the resolver to find which service to use
> (files, DNS or NIS). I'm very confused at this point and don't know what
> to believe...


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