I have a local dns with a slave zone forwarding to my w0rkplace across a vpnc
tunnel.
Together with adding the work domain to the resolv.conf searchlist, I can do full
(and reverse) DNS lookups.
[walter@woodpecker ~]$ ping wsppb177c
PING wsppb177c.zds.ages.at (172.18.55.209) 56(84) bytes of data.
64 bytes from wsppb177c.ages.at (172.18.55.209): icmp_req=1 ttl=63 time=14.8 ms
64 bytes from wsppb177c.ages.at (172.18.55.209): icmp_req=2 ttl=63 time=14.5 ms
^C
--- wsppb177c.zds.ages.at ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 14.529/14.666/14.804/0.183 ms
[walter@woodpecker ~]$ nmap wsppb177c

Starting Nmap 5.21 ( http://nmap.org ) at 2011-03-12 13:28 CET
Nmap scan report for wsppb177c (172.18.55.209)
Host is up (0.047s latency).
Not shown: 992 closed ports
PORT STATE SERVICE
22/tcp open ssh
.....
Nmap done: 1 IP address (1 host up) scanned in 2.09 seconds

But trying ssh to the same (linux) box gives:
[walter@woodpecker ~]$ ssh wsppb177c
ssh: Could not resolve hostname wsppb177c: Name or service not known
Yes, getent hosts works:
[walter@woodpecker ~]$ getent hosts wsppb177c
172.18.55.209 wsppb177c.zds.ages.at
and
[walter@woodpecker ~]$ host 172.18.55.209
209.55.18.172.in-addr.arpa domain name pointer wsppb177c.ages.at.
works as well (though omitting the zds. part),
but
[walter@woodpecker ~]$ export LC_ALL=C; rdesktop wsppb177c
ERROR: getaddrinfo: Name or service not known

/etc/nsswitch.conf contains files dns entries for hosts resolution.

Some bug in Mandriva or PEBKAC? ;-)

If you have to ask, I think you've already answered! ;-)
Just kidding...

This is unusual. Would you include the contents of your
/etc/resolv.conf and /etc/nsswitch.conf files?

First (someone was worried about obfuscating the IPs) - these are all addresses of the "private" range and the DNS is inside the vpn as well.

Ok. here my /etc/resolv.conf:

# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 127.0.0.1
search zds.ages.at ages.at woodpecker.dyndns-at-home.com
nameserver 172.18.64.50
nameserver 172.18.64.49
nameserver 195.34.133.21
search woodpecker.dyndns-at-home.com zds.ages.at ages.at

(I should of course disable the resolvconf "service" and omit the automagical part ... but I tried and it didn't matter)

/etc/nsswitch.confasswd: compat
shadow: files nis
group: compat

hosts: files dns wins mdns4_minimal
networks: files dns

services: files
protocols: files
rpc: files
ethers: files
netmasks: files
netgroup: files
publickey: files

bootparams: files
automount: files dns nis
aliases: files dns

But then, again, dns resolution seems to work ...

Anything I can do to debug?

I don't see anything that doesn't look right, apart from the two
search lines in resolv.conf. That might be right, but I have
never seen a resolv.conf with two search lines.

I'm not sure how to go about debugging this. Just for grins I
would try putting entries in your /etc/hosts file to see if that
works.

For example:

172.18.55.209 wsppb177c.zds.ages.at wsppb177c