DC Redundancy

[FN-GM]

Hi all,

 

In the network there is 3 Windows Server 2008 Domain Controllers. Today one DC with all the FSnO roles went down due to power outage. Nobody could logon. The other 2 servers are Global Catalogue servers.

 

My question is why did DNS stop working for clients and why could no body logon? If you made the other DC's GC i thought they would handle logons when the other isnt arround.

 

Thanks

 

Z

[rusty155]

Does the one that went down handle your DHCP?

[FN-GM]

Does the one that went down handle your DHCP?

 

No

 

Thanks

 

Z

[sammy]

Hi there,

 

was DNS only running on 1 server ?

 

Sam

[FN-GM]

Hi there,

 

was DNS only running on 1 server ?

 

Sam

 

No its on all 3 servers and clients are set to point DNS at all 3 servers. The server that went down was the first DNS server to use though.

[sammy]

This stinks of a DNS issue to me, perhaps some issue with the Round robin configuration or an incorrect record in the DNS which is preventing clients from querying the other DNS servers in the event of a failure. I know round robin is on by default, so theoreticaly the other 2 servers with the GC should point clients to the correct DNS server and provide logon authentication....so in my mind the only reason this wouldnt work is if GC was not pointing clients to the other DNS servers.

[FN-GM]

This stinks of a DNS issue to me, perhaps some issue with the Round robin configuration or an incorrect record in the DNS which is preventing clients from querying the other DNS servers in the event of a failure. I know round robin is on by default, so theoreticaly the other 2 servers with the GC should point clients to the correct DNS server and provide logon authentication....so in my mind the only reason this wouldnt work is if GC was not pointing clients to the other DNS servers.

 

thats what i thought but everything seems ok

[teejay]

The easiest way I've found to get over this sort of problem is to deploy a hosts file to you desktop PC's with the core servers in it. Not necessarily the nicest solution, but it works very well.

[matt40k]

Sounds like someone should of tested the "redundancy" whilst still in the deployment stage

 

Have you tried checking the client, they may need dns flush.

[FN-GM]

Sounds like someone should of tested the "redundancy" whilst still in the deployment stage

 

Have you tried checking the client, they may need dns flush.

 

The thing is i shouldn't need to flush the DNS. when you reboot the client it doesnt let you log on.

 

Z

[DrPerceptron]

Are all of the services and what not running on the two other DC's?

 

Do the event logs on either of those have anything to say?

 

What do the clients say, if anything?

[FN-GM]

Clients cant find the domain, event logs throw up nothing.

[Slartibartfast]

What's the DNS configuration on the DC network interfaces? How are the DNS servers ordered on there?

[Michael]

On a workstation, if you do:

 

ipconfig /all

 

from a command prompt, it should list all internal and external DNS servers. In DHCP, make sure your DNS servers are all listed.

 

Also, each server should look at itself as primary and the other two secondary and then any external DNS servers. If the other two are looking at the DC that went down, this would create a problem.

[boomam]

Are the other DNS servers specified in DHCP for the clients?

[FN-GM]

since htis post i forgot about this problem will look into it more.

 

DNS is set on clients for all my DC's as it should. The DNS looks in pretty good shape to be honest.

 

What's the DNS configuration on the DC network interfaces? How are the DNS servers ordered on there?

 

All DNS servers point to themselves.