nslookup not working on client machines only

[Nicolas]

Hello,

I've set up a FreeBSD box to provide my home network a NAT access to the
Internet and a DNS caching-only server with bind 8.3.7 (among other things).

It's working perfectly but today I noticed something that I do not
understand. When trying to $ nslookup google.com on a client host,
here's what it says :

8<--
nicolas at fsol$ nslookup google.com
*** Can't find server name for address 192.168.0.1: Non-existent host/domain
*** Can't find server name for address ::: No response from server
*** Default servers are not available
nicolas at fsol$
-->8

Now, trying the same thing directly on the DNS box :

8<--
root at earth$ nslookup google.com
Server:         192.168.0.1
Address:        192.168.0.1#53

Non-authoritative answer:
Name:   google.com
Address: 216.239.57.99
Name:   google.com
Address: 216.239.37.99
Name:   google.com
Address: 216.239.39.99

root at earth$
-->8

The resolv.conf files are the same on the 2 boxes :

8<--
nicolas at fsol$ cat /etc/resolv.conf
search serpe.org
nameserver 192.168.0.1
nicolas at fsol$

root at earth$ cat /etc/resolv.conf
search serpe.org
nameserver 192.168.0.1
root at earth$
-->8

Given this, I do not understand why it works on the DNS box and not on
the client.

Thank you very much in advance for your help!

Nicolas.