There is no such thing as a "DNS range." A DNS server is a machine with one or more IP addresses, running DNS software, and that's that. VERY few DNS servers restrict usage (e.g., you can normally use any DNS server from any ISP, firewalls notwithstanding).

Try entering your ISP's DNS server address(es) manually in the G3. Your cable company should be able to give you a couple of DNS addresses if you ask. You could also try to discover the DNS server's IP address on your G4, using the Terminal. Type "nslookup" and see what it tells you (for example, mine returns "tycho.concentric.net" and the IP address of the name server). (Type "exit" to leave the nslookup utility.)

tooki