If you're DNS servers are not authoritative name servers for the domains you host web sites for, you don't need to worry about DNS.
All you need to do, is configure an A record (aka. Host record) for
www.domain.com and point it to the public IP of the web server.
I'm not sure I understand your question. If you are setting up DNS servers for internal use (answering lookups from local machines with internet access), this is what you need
- Create forwarders on each DNS Server.
- Check "Disable Recursion" if you want all queries forwarded (instead of root hint lookups).
Now, all queries for domains for which you do NOT have a forward lookup zone OR a conditional forwarder, will be forwarded to the "default" servers configured in step 1