host versus nslookup

Lightner, Jeff JLightner at
Sat Oct 15 18:15:24 UTC 2011

Even more fun on HP-UX is that in addition to the hosts line in nsswitch.conf they allow for a separate line called ipnodes used by IPv6 routines whereas hosts is only used by the older routines (gethostbyname etc...).   It bit me when using NetBackup 7 because Symantec started using the IPv6 routines there where they hadn't in 6.5.   HP's nslookup kept returning the correct entry from /etc/hosts but NBU refused to see it because I didn't have the ipnodes line.

-----Original Message-----
From: at [ at] On Behalf Of Cathy Almond
Sent: Saturday, October 15, 2011 6:00 AM
To: bind-users at
Subject: Re: host versus nslookup

On 12/10/11 23:09, Kevin Darcy wrote:
> As far as I know, only HP-UX has hacked nslookup to look at /etc/hosts.
> And I don't think it even looks at the "switch" file or other naming
> sources (e.g. Yellow Plague). HP-UX's nslookup "enhancement" is a
> one-off, I believe.
For the record, on HP-UX it does use the switch file (unless you
specifically tell it to do something different when you run it).

But its use as a troubleshooting tool is limited at best (misleading and
confusing at worst) in that environment for testing how application
resolution will work.  And this is because it uses its own logic and not
the high level resolver APIs that applications call.

(And even if it did use the high level resolver APIs - it wouldn't
necessarily be using them with the same options that an application does
anyway - particularly around IPv6 versus IPv4).
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