Here's my scenario: my host is a Windows XP, and I have a guest OS of Ubuntu 8.04. I'm using VirtualBox for this.
I have successfully configured my DNS server in my Ubuntu OS. And if I do the following commands, all of them will give me the corresponding IP address of my DNS server.
dig example.com nslookup ns1.example.com host ns1.example.com
But when I try to ping my DNS server from the host (Windows XP), it says it cannot find the DNS server. Also, if I try to ping my DNS server from another PC, it does not seem to find the DNS server as well.