DC Stopped Working No DNS and No AD Changes

Posted on 2009-04-16
Last Modified: 2012-05-06

we have 4 DCs. the one that contains all the FSMO roles has stopped working properly.

it no longer works as a DNS and when i add a machine to the domain it no longer shows in the computers OU.

if i do an nslookup on the troubled DC that is having trouble it will provide a correct response from itself. however, if i do an nslookup on a workstation, it will return "DNS request timed out" and then resolve to the secondary DC which will return the correct response.

if i attempt to add a machine to the domain using the troubled DC it will prompt me for authentication and then respond with "the network path was not found". but, if i point the workstation to another DC it add the macine to AD and that will be propagated to the other 2 DCs, but not to the troubled DC.

i can ping the troubled DC just fine.

any thoughts?

Question by:ysdadmin
    LVL 13

    Expert Comment

    Have you added to ISP's DNS address into DC's DNS setting ?

    Your clients need to have the DC as default DNS. Your DC should have your ISP's DNS-servers configured as forwarders.
    LVL 38

    Expert Comment

    Sounds like a firewall block, or the wrong preferred DNS server on the DC itself (as rhinoceros was saying).

    Author Comment

    thanks for the ideas.

    but, turns out it was an update to the antivirus software that killed it. once i removed the AV the DC came back online. the weird thing is that the other 3 DC had no problem with the AV update.

    must be something about this DC having all the FSMOs and ? that doesn't do well with AV?

    LVL 13

    Accepted Solution

    I think the problem is not come from AV....

    Have you tried to check your DNS setting from Master DC (FMSOs holder)  ?

    It is likely the following setting?
    Master DC

    Secondary DC

    If true, so why you get the result...
    "it will return "DNS request timed out" and then resolve to the secondary DC which will return the correct response."
    Because only secondary DC is pointed to correct INTERNAL DNS for resolve workstation. You should change ISP DNS setting as forwarders, not preferred DNS server.

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