Broken DHCP server

[Jawloms]

Two DCs on site. Both Server 2016. One is a DHCP server. Did a bunch of updates yesterday and now it won't hand out IP addresses. Everything on the server indicates all is well, nothing in the event logs (apart from IPv6 being a dynamic address) but when doing an "ipconfig /renew" on a client it says the DHCP request timed out. This is wireless or wired. If I make the other a DHCP server (which I haven't done updates on!), that works fine. This obviously points to an update, but I can't find anything indicating one may have an issue, and I haven't done updates on it since mid April so it pulled a few in. Wondered if anyone had an idea before I start uninstalling them one-by-one?

 

Stuart

[Jawloms]

I do have half a dozen of these in the logs;

 

Certificate for local system with Thumbprint 07 59 ad 2e f5 39 91 f9 79 c4 8d 2f 31 5f 35 a7 b2 41 6a d7 is about to expire or already expired.

 

And have found results when Googling ranging from unhelpful to "You can ignore this".

[pantscat]

Hey - have you just tried restarting the DHCP Server service?

[Jawloms]

Yes, a few times.

 

I have also just noticed that if I "unauthorize" it, it stays showing as authorized in the GUI. If I try and unauthorize it again it says "The parameter is incorrect" and it is only when I restart the service it actually updates the GUI. No amount of "refresh" sorts it, it has to be a service restart.

[pantscat]

Interesting.

 

What does netsh dhcp show server show when you've unauthorised it?

[3s-gtech]

Can you export the DHCP config and just run it on the other server? Or even put the two into a failover configuration and see what happens?

 

DHCP is usually a fairly disposable service on Windows - if you have to nuke it and try again, it’s not too bad - especially if you have the config.

 

I’ve not run it on 2016 to have much experience specifically - I went from 2012 R2 to 2019.

[Jawloms]

Interesting.

 

What does netsh dhcp show server show when you've unauthorised it?

 

It no longer lists it.

 

Can you export the DHCP config and just run it on the other server? Or even put the two into a failover configuration and see what happens?

 

DHCP is usually a fairly disposable service on Windows - if you have to nuke it and try again, it’s not too bad - especially if you have the config.

 

I’ve not run it on 2016 to have much experience specifically - I went from 2012 R2 to 2019.

 

I may well just move DHCP over to the other DC, it just concerns me it stopped working, and is there anything else underneath which isn't working either? Replication and DNS seem fine, so I'm hoping I'm OK.

[Katy]

Can you check the bindings, make sure it's actually bound and listening to the right interface? I've had it randomly decide it is no longer bound before.

[Jawloms]

Can you check the bindings, make sure it's actually bound and listening to the right interface? I've had it randomly decide it is no longer bound before.

 

Yup, checked that.

 

Going to remove the role and reinstall and see if that makes an difference.

[chaplic]

Could it have got in a pickle on reboot and thinking it's on a public network, thus applying firewall?

[Jawloms]

Could it have got in a pickle on reboot and thinking it's on a public network, thus applying firewall?

 

It appears not.