Bizzare Issue

[keyboards]

Please help, since last Wednesday, we came in to find the main DC/AD/internet server had pretty much hung but still providing internet etc, we restarted it, since then, we've got loads of machines that are fine then randomly lose network connection and/or internet, as soon as you restart them they come back

 

Any ideas, I'm desperate

[Griff]

I would first start with the Event Viewer on the server see if you can find any errors or warnings happening around the time you were having issues. Use this to try and help diagnose the problem. The other thing it could be is a duplicate IP address so jump into your DHCP and see if there are any BAD_ADDRESS warnings that might indicate a duplicated IP.

[keyboards]

I would first start with the Event Viewer on the server see if you can find any errors or warnings happening around the time you were having issues. Use this to try and help diagnose the problem. The other thing it could be is a duplicate IP address so jump into your DHCP and see if there are any BAD_ADDRESS warnings that might indicate a duplicated IP.

 

Thanks very much we did have about 10 bad addresses, what are our next steps

 

Appreicate your help, I'm knackred

[keyboards]

This appears when it first started

 

The DNS server has encountered a critical error from the Active Directory. Check that the Active Directory is functioning properly. The extended error debug information (which may be empty) is "". The event data contains the error.

[Guest Guest]

This appears when it first started

 

The DNS server has encountered a critical error from the Active Directory. Check that the Active Directory is functioning properly. The extended error debug information (which may be empty) is "". The event data contains the error.

We get that on every reboot of our DCs, I've seen it on multiple domains so I assume it's normal

[HPlum78]

Yeah that's a race condition where the DNS service starts faster than AD essentially. I would guess that you are pointing DNS to the local loop back adapter rather than the DC's private address.

[Guest Guest]

Yeah that's a race condition where the DNS service starts faster than AD essentially. I would guess that you are pointing DNS to the local loop back adapter rather than the DC's private address.

No, each DC points to the other DC as primary and its own private address as secondary

[HPlum78]

That also don't match up with what you describe in your initial post, the randomly lose network interest me and think that needs unpicking initially. Especially if the DC in question is still running as expected also you should be able to take a DC outage without impacting your clients (I would hope).

[HPlum78]

@kieran1990 so other guesses are ipv 6 has been disabled or you have multiple NIC installed and the bindings are not correct or unused NICs are not disabled...

[HPlum78]

Totally missed the posts around DHCP! Can you be sure that you have not statically assigned ip addresses to devices and left those in the DHCP pool?

[keyboards]

Sorry on phone

So it's a VM, with one virtual nic

 

It seems totally random we'll get a few machines each day, randomly just lose internet and network connection but still think they're connected, as soon as you restart it, it solves it, so say 98% of our network seems fine so to speak but it's a few machines every day

 

On the DHCP we did have about 10 bad addresses

 

We shouldn't of assigned static ip's

[Griff]

Sorry on phone

So it's a VM, with one virtual nic

 

It seems totally random we'll get a few machines each day, randomly just lose internet and network connection but still think they're connected, as soon as you restart it, it solves it, so say 98% of our network seems fine so to speak but it's a few machines every day

 

On the DHCP we did have about 10 bad addresses

 

We shouldn't of assigned static ip's

 

There is nothing wrong with assigning statics don't worry about that, its just making sure you exclude them from the DHCP distribution and put them on Reservations. I am 100% sure we had a similar issue that you're describing and I think we had to poke around in our DNS a fair bit and found that the Server Aging/Scavenging was all out of whack ours is now 7 days on both and ticked on to Scavenge stale resource records.

[TwistedHelixis]

Do you have any duplicate IPs in DNS?

[keyboards]

Thanks for alll your help, think we've solved this by restarting the DNS and dhcp services, got a few bad addresses but had none for a few days now