weird resolv.conf issue with unavailable DNS server

[Stephanie L Davenport]

We have three DNS servers listed in our /etc/resolv.conf file. Yesterday, the last one in the list went offline. But, the first two were running fine.

Out of our three production UNIX machines, only one had issues with the reverse lookups. The other two didn't have any delay with telnet.

The /etc/resolv.conf and /etc/nsswitch.conf files are exactly the same on all three machines. What could cause one machine to have issues and not the other two?

nsswitch.conf:
hosts: files [NOTFOUND=continue TRYAGAIN=continue] dns [NOTFOUND=contin
ue TRYAGAIN=continue]
#hosts: files
aliases: files
services: files
protocols: files
networks: files
rpc: files
netgroup: files

This is exactly the same on all three production UNIX servers.

[Steven E. Protter]

Shalom,

I'd like to see the relevant log entries on two of the servers.

There should be clues.

Knowing that the third DNS server is down, one might take it and comment it out and see how things change.

I would surmise that this third DNS server is the only one of the three providing reverse lookup information or its BIND/DNS configuration is not permitting full access to the Unix host having the problem.

SEP

[Stephanie L Davenport]

Steven,

But, shouldn't it have gotten the reverse lookup information from the first two DNS servers before reaching the third one?

And, if it is an issue with the DNS server itself, why did telnet work correctly for our other two production UNIX machines and not this one?

All three DNS servers are windows based (not UNIX).

Which log files?