This is a common error made by many so don’t get too frustrated!
Rules of the game:
1. Never point local machines to your ISP’s DNS server. The ISP DNS server cannot resolve interal DNS requests.
2. Never set an ISP’s DNS address as a DNS server on any server network adapter.
Knowing the rules here is what you do…
1. Make sure that DNS is installed and running properly on your LAN.
2. Point your DNS server to itself as the primary DNS.
3. Add your ISP’s DNS server addresses as “Forwarders” in your DNS server configuration.
4. Point all other servers and workstations to the DNS server on your LAN.