DHCP not updating AD DNS

I am having an issue with DNS.
It's worked for yonks and nothing has changed of late - except a power failure...

Site A server A is a 2008 PDC. It's doing DNS & DHCP, Server B is a 2008 BDC also running DHCP
Site B server C is a 2008 BDC doing DNS & DHCP

DNS is not being updated though.

I killed al leases last night and this morning no updates in DNS.
Clients on site A or B are getting leases from only the legitimate servers. I've checked
I then disabled DHCP on Server B just in case.
Machines join the LAN and get lease but still DNS not being updated.
AD appears to be working fine - I can add machines and they are duly replicated. DFS works

I've check security settings and the 3 DC's are allowed to update DNS.
I've also set DHCP to forefullyupdate DNS regardless if the client asks or not.

Also DNS timestamps.
If a user gets a lease yesterday say and then another elase today - say the same IP
Should the timestamp in DNS not be updated also? Some have beenupdated today
but others havent or are missing completely
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Please verify in your DHCP Console -> IP V4 Properties -> DNS - 'Always dynamically update DNS A and PTR Records' option is set.
MajicthiseAuthor Commented:
Hi Thanks for the post.
It is ticked - Thats what I meant by

I've also set DHCP to forefullyupdate DNS regardless if the client asks or not.
MajicthiseAuthor Commented:
Also meant to say stopped and started the usual DNS/DHCP etc and made no difference
Check if dns zone (domain.com) and (_msdcs.domain.com) is set to secure dynamic update only
Add both DHCP servers in DNS Update proxy group on domain controller
Set credentials in DHCP console, otherwise your dhcp-dns integration options will not help to update records
Check below post for how to achieve this and to understand dns dhcp integration and other options to set correctly

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MajicthiseAuthor Commented:
Adding and re-entering credentials seems to have sorted the issue.

I can honestly say I've never added any server to DNS Update group
And it's worked flawlessly for about 3 years.

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