A flag of "0" means the client updates the A record and requests that the server update the PTR record on its behalf. Also in the DHCP scope make sure == Click the DNS tab, click Properties, and then click to select the Dynamically update DNS A and PTR records only if requested by the DHCP clients check box == is set.
This would mean when the default flag of "0" comes in the server will then try to register the PTR record with the DNS server(s) it is configured to update.
The dynamic update client registers an address resource record (A RR). the DHCP server can be configured to instruct the client to allow the server to register both records with the DNS.The zone at this server must be obtained from another DNS server that hosts the zone.This DNS server must have network access to the remote DNS server to copy the authoritative name server information about the zone.If you find that you can not resolve IP’s back to a name on your network check your DNS REVERSE LOOKUP ZONE.If there are missing entries, you likely have your DHCP missing one of two settings: This is required if you have DHCP installed on a Domain Controller.