DHCP Problems not updating DNS/Pencil on Ip Leases

[Unique01]

Cheers,

 

Facing a problem in our network, with 2 of the 3 windows 2008 DHCP servers.

- The one that is inserted on a Domain Controller is working Flawlessly, givind ip and updating new records to the DNS

- The other 2, randomly update Dns for some leases but after DHCP Database Cleanup (which is defined to ocurre every hour), they start to log Dns Update Failed messages, even to the ones they have successfuly updated in the last our.

 

What we've done so far:

 

1- Checked Dns reverse lookup zones and they exist ( some didn't existed and were created) - Result= The same problems

2- Configured Dhcp credentials with admin rights to write in Dns - Result= The same problems

3- Added DHCP's to the DnsUpdateProxy Group - Result= Same Problems

4- Deleted leases both in Dns, forward and lookup zones, and on the DHCP to force new assignment and renew - Result= Same Problems

 

Every sigle DHCP is defined to automatically update Dns and Ptr records.

 

Any ideas would be much appreciated.