AD, DNS Server Intergration

Dear All,

We have a local TCP/IP network with 2 DC's (DNS servers) and for some reason , when one DC is down the Internet goes down, and we cannot connect to a application server held on another server.

This defies having 2 DC's.

I have checked the IP settings of the servers and they all look ok with the same gateway and DNS entries listed within the DC's and our application server.

It's a bit strange as we put 2 DC's in to stop this from happening, it looks like one DC is a master.

The 2 DC's do appear within AD, as DC's.

Any ideas please?

Who is Participating?
Krzysztof PytkoSenior Active Directory EngineerCommented:
You need to configure forwarders on both DNS servers to allow users accessing the Internet. Probably one of your DNS servers is configured for that.

Please follow this instructions to set up forwarders on the other DNS server too

Make sure that both DNS servers are entered in the DNS settings of the clients.  (This includes checking the DHCP settings, if any.)

Also, make sure DNS queries from both servers are permitted through your firewall.

Test external queries on both DNS servers.   (Start DNS console -> properties of the DNS server -> monitoring -> a recursive query to other DNS severs -> test now)  Keep at it until this is successful.
piyushranusriSystem Cloud SpecialistCommented:
important thing to check

if you are using DHCP make sure client must use second dns ip.
preferred dns will be your first dns server and alternate dns server ips.

and is both DC are on same location or different location because you mention internet goes down.
make active/passive cluster.
are they on physical or virtual ?
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