Servers Can't Resolve Own Hostnames or Network

[neilherbertuk]

Hello all,

 

Got a rather puzzling and urgent issue. On Wednesday night we had a powercut which took out our Primary Domain Controller (win2k8r2). We're back up and running on the secondary server (now primary) running server 2003. We also have a new win 2k8 r2 server back up with the same configuration as before but this has for now been left as a secondary dc. It has the exact same setup as before.

 

We have a fair few servers but we are only having issues with 2 of them, both running win 2k8 r2, one running our SQL server and the other our Exchange 2010 server. Both of these servers have gone mad and can't resolve any hostnames including it's own or even localhost! On the exchange server I've tried to reset the TCP/IP stack and had a specialist looking at it too. Under nslookup it says Default Server: Unknown. Because of the hostname resolution issues the servers cant talk to AD or the internet which is obviously stopping both sql and exchange from starting back up.

 

Wondered if anyone else had come across this and might help point us in the right direction?

 

Neil

Edited August 3, 2012 by neilherbertuk

[mac_shinobi]

Not sure if this is an option but restore from the last successful backup before it went south ?

[neilherbertuk]

Not sure if this is an option but restore from the last successful backup before it went south ?

 

That is an option but I really would like to keep that as a last resort!

[Achandler]

So the problem is purely resolving the names, it can ping addresses etc if you provide it with an IP?

 

If so I assume you have changed all the DNS servers with no luck, and assuming pinging "localhost" also doesn't work then it seems like the DNS client on the servers has gone haywire, you have tried the in built repair utility to check the windows files to?

[neilherbertuk]

Hi Achandler

 

Yes we can ping IP addresses without an issue it's purely down to hostname resolution / dns. Like our Exchange server won't come back online as the Active Directory Topology service wont start. In the eventlog it lists the 2 domain controllers but says it cant find them. Same as websites, it cant resolve domain names. Yet you can connect to the mailserver using it's hostname from another computer (rdp) and get the owa login box through the browser.

 

I haven't yet tried an sfc but that will be on the cards shortly.

 

Neil

[Achandler]

and you have definitely checked that they are pointing to the right DNS on the NICs right?

 

I only ask because I have seen people not able to ping localhost but able to ping everything else via hostname.

Edited August 3, 2012 by Achandler

[sukh]

1. What does the 2080 event say in the app log on the Exch server?

2. What version of Exch?

3. As a test can you stick in a host entry for one GC in-site and test?

4. How did you try to reset the IP stack?

5. When you do an ipconfig /all does it show the correct DNS servers?

[neilherbertuk]

Yes DNS is set correctly but it can not ping any hostname at all! I've just put one of the servers onto dhcp to see if it could resolve anything without luck.

[Achandler]

I would reset the stack again. Then check that the ipconfig is all correct. Have you tried flushing DNS as well to make sure you are definitely getting a clean copy again.

[sukh]

Yes DNS is set correctly but it can not ping any hostname at all! I've just put one of the servers onto dhcp to see if it could resolve anything without luck.

 

What about the other questions?

[Achandler]

Well he has Exchange 2010, he mentioned earlier.

[sukh]

Well he has Exchange 2010, he mentioned earlier.

 

Detailed info like SP level UR etc..makes it easier when troubleshooting any issue when Exch is installed, many issues depending on the level you're on. However, in this case it seems more on a DNS issue however knowing the env always helps me.

[twin--turbo]

what happens on an NSLOOKUP?

 

rOB

[neilherbertuk]

Sorry sukh, didn't see your reply.

 

1) Not getting a 2080 error (though the specialist who has been looking did clear the logs about half hour ago)

2) As I get an initalisation error when loading the Exchange Console I can only tell you its Exchange 2010

4) I reset the tcp/ip stack using the netsh command "netsh int ip reset"

5) Yes the dns ip addresses are manually set. ipconfig /all does show the correct settings.

 

As for 3 not sure how to do that. My boss who should know how to do that is on holiday! So by myself!

 

As for enviroment its windows 2008 r2 standard with sp1

[twin--turbo]

Also try a telnet to port 53 on the DNS server.

 

you should get a cursor rather than a "connecting"

[neilherbertuk]

ok nslookup

 

C:\Users\administrator.DOMAIN>nslookup

Default Server: UnKnown

Address: x.x.128.251

 

> mailserver

Server: UnKnown

Address: x.x.128.251

 

*** UnKnown can't find mailserver: No response from server

> domaincontroller

Server: UnKnown

Address: x.x.128.251

 

*** UnKnown can't find domaincontroller: No response from server

>

 

I've made a few changes to save erm, embarisment lol. The ip x.x.128.251 is the ip for domaincontroller (thats the new secondary server, its using the same name and ip as the dc that crashed)

 

Using telnet

 

Connecting To x.x.128.251...Could not open connection to the host, on port 53.

The requested service provider could not be loaded or initialized.

 

Windows Firewall on both DCs are turned off...

[sukh]

1. Can you move TCP/IP from the NIC adapter and resinstall, re-IP and then test?

2. Can you see if IPv6 is enabled or disabled?

3. Can you update the NIC drivers if they aren't running the latest drivers?

[neilherbertuk]

Bare with me sukh, I will have to do that locally. IPv6 is disabled. It's disabled across the entire network. Saying that if you ping the mailserver from the win2k8 dc it shows an ipv6 address rather than ipv4 which is very very odd...

[neilherbertuk]

I've removed ipv4 and reinstalled it on the mailserver with no change to the issue.

[Achandler]

Removing the NIC from device manager and re-adding is also an option, this would reset everything to do with the NIC itself.

[neilherbertuk]

I'll give that ago too achandler. Again will have to do it locally will let you know if it changes anything.

[sukh]

Can you use the windows 2003 DC as the primary instead of the 2008 if it has DNS too?

[neilherbertuk]

I've uninstalled and reinstalled the NIC and it seems to be able to ping itself and any hostname I throw at it. We will see what happens after a reboot.

[neilherbertuk]

Setting the primary dns to the 2003 server (x.x.128.252) didn't make a difference.

[sukh]

I've uninstalled and reinstalled the NIC and it seems to be able to ping itself and any hostname I throw at it. We will see what happens after a reboot.

 

So is it working?