When I'm connecting to the VPN at work, I frequently run into problems with sites blocked by OpenDNS, and also being limited to the DNS entries on their DNS server.
I'm wondering if there is a way to have domain-name resolution go to one server, and if that name lookup fails, to have it try another. Solving this problem would basically let you to use the union of DNS entries from multiple servers.
Caveat: It seems like a prioritized list of DNS servers in
/etc/resolv.conf will not fall through to subsequent entries if the name lookup fails, it will only if the primary DNS server is actually down.