Dns not updating from dhcp
You can use the following registry subkey to modify the TTL value: HKEY_LOCAL_MACHINE\SYSTEM\Current Control Set\Services\Tcpip\Parameters\Default Registration TTL . Scavenging Refresh and No Refresh settings must be equal to or less than the lease period.
For example, using the default DHCP lease period of 8 days with a 7day scavenge setting, is perfect.
If there is no timestamp, such as a manually created, static record, it will not get scavenged.
Also, if all servers, including DCs, are automatically updating their own record, then there is no fear of losing their records, because for one, their records (timestamps) are current, therefore scavenging won’t touch them, and two, Windows Servers by default will update their records every 24 hours, with the exception of domain controllers at every 60 minutes.
This is because DHCP doesn’t own the record, the client does, even though DHCP registered it.
The way to get around this is you can configure DHCP’s Option 081 to update the record for all client, no matter if the client asks or not.
This applies to Windows 2000 Professional and all newer operating systems.
For domain controllers, due to the importance of keeping up to date and accurate SRV and other records, the Netlogon service will attempt to update these records every 60 minutes.
Despite it being a DHCP Option, it’s not found in a DHCP server, scope or class option. After configuring the above provedure, the credentials and Dns Update Proxy group configuratuion will not update current or delete duplicate records. If DHCP is on a Windows 2008 R2 DC, to protect the DC when using the Dns Update Proxy group, you must secure the group by running: dnscmd /config /Open Acl On Proxy Updates 0 Using “DHCP Name Protection.” will register A and PTR record on behalf of a client, and will prevent a workstation (non-Windows) Name Squatting, meaning using a name that another machine (non-Windows or Windows) client that DHCP already registered , from registering it’s name.By default, on a computer that is running Windows XP/2003 or newer, the Default Registration Refresh Interval key value controls this (except Windows 2000, whichdoes not have this key but can be added), and is set by default to 1 day.