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ISP DNS and LAN DNS

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6 replies

by mojochang

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I have a single domain and one W2K DNS server, also few ISP DNS IP address. I configure "Preferred DNS Server" under TCP/IP by using ISP's DNS IP on both workstations and Servers (included DNS server itself) so that we can access Internet. is that correct? However, If I set our DNS's IP address as "preferred DNS server", then unable to access Internet. what's the relationship between our DNS IP and ISP's IPs. how can i get it right?

6 replies

by mattp

If you only have one DNS server on your internal network the best way to implement DNS is to enable forwards on the DNS server.

Instruct the servers and clients to use the IP address of the internal DNS server.

On the DNS server, open DNS and expand the server. Rt click on the server and go to the "Forwards" tab. Check the box that enalbes forwards. Then type in 1...2...or 3 IP address of the ISP's servers.

If the box is unabled to be checked then your server is a "root" server. You can tell when you expand your forward lookup zone there is a zone named "." If you delete this zone then reboot the server, the forwarders box will be enabled and you can implement forwards.

What this does is allow your internal DNS to resolve queries for your internal clients by forwarding unknown queries to the external DNS servers.

by pan 13 x

the inturnal dns is a refferance to your items in house. this is not public to the world. say you want to run a web server in your domain. and wanted the server to have the name "intranet" then your address for the server would be (intranet."your-domain".com) the outside would have no clue nor can hit it. the isp dns is a collection of web addresses and names that can be hit from anywhere. these doamin are registered. The problem you are having is that your dns server is not setup to talk to outside dns servers and to forward the info to them. In the mmc for the dns right click on the server and select properities. the you will find a tab for forwarding. enter the ip address of the isp address you know to work. this will cause the dns server you have to forward all request that the server can not understand to the outside dns for name resolution. you know can set you server and workstations to use just you dns server. if you only have one dns server inhouse. I would be safe and eneter the isp dns in the secondary server address , just in case you dns server goes down and is not forwarding to the outside. this you do not have to do .. it will work fine with out it but the other is nothing more then a back up.

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