DNS Problems

[stuartp44]

I have a AD domain that constists of 2 DC's one of which is a DHCP and both of them are DNS Servers, over the sixth week holiday we have changed our network from a flat network to seprated broadcast domains. Since we changed we are having issues with our DNS/DHCP server, the problem being the dynamic updaing of the DNS server. When you see the event log from the DHCP you can see that its not updating the DNS, however when you restart the DHCP service and recheck the event log it updates fine. After a bit you get a failure and then most DNS updates after that fail, however some update ok.

[Michael]

I presume that the servers are replicating OK and that a working trust is in place?

[stuartp44]

There is only one domain its just split into different VLANS (One for Main School, One for Sixth Form, One for Servers...)

[Michael]

Have a look here, you may be affected by this.

[stuartp44]

Yeh i allready seen that, and you are right i am expecing that on my clients. However the servers are able to talk to each other as they used to as all of them are on the same VLAN, and this problem is between the DHCP server and the DNS server.

[_Adam_]

There is a bit it could be, but just basing it on what you wrote have you updated your subnets under AD Sites and Services to include the new VLAN subnets?

[stuartp44]

The problem was down to the reverse DNS,

 

I have two large subnets on my network 172.16.56.0/21 and 172.16.24.0/21, due to their size i didn’t account for all the reverse DNS entries and only placed 172.16.24.0 into the Reverse DNS Entry. What should have been in there was 172.16.24/25/26/27/28/29/30/31 and so on. What this turned out to be is when the DHCP server was doing its database clean it attempted to do a bulk DNS update, but unfortunately one failed and the rest got queued. Somewhere i spotted a statement "If there is a DNS Queue, until the queue has gone any further DNS queries will fail", and surprise surprise it started to work straight way. Anyhow learnt a lot from this and as part of the progress i sorted some problems i didn’t see, but everything is now working fine.