This happens even though DHCP registered the record.
This is because DHCP doesn’t own the record, the client does, even though DHCP registered it. If you have Windows 2008 R2, in addition to configuring the DNS tab to force registration, you still must configure credentials and add the server to the Dns Update Proxy group.
Ace Fekay, MCT, MVP, MCITP EA, Exchange 2010 Enterprise Administrator, MCTS Windows 2008, Exchange 2010 & Exchange 2007, MCSE 2003/2000, MCSA Messaging 2003 Microsoft Certified Trainer Microsoft MVP: Directory Services Active Directory, Exchange and Windows Infrastructure Engineer Compiled 4/2006, recompiled 7/2009, & 1/4/201011/30/2011 – added DHCP credentials and DHCP/DNS tab properties screenshots.3/10/2012 – Added enabling DNS scavenging screenshots.8/22/2012 – Verified with a Microsoft enginner, we need to use the Dns Update Proxy group and configure credentials to work, not one or the other. Also fixed missing screenshots8/3/2012 – Additional info about DHCP Name Protection and that it requires Credentials, Dns Update Proxy, but more so to secure the Dns Update Proxy group .
When a client shuts down, and later returns past the lease time, it may get a different IP address.
If there is a problem with PTRs getting updated even after configuring credentials, please see this article: DHCP server processes expired PTR resource records in Windows Server 2003 . Name squatting does not present a problem on a homogeneous Windows network where Active Directory® Domain Services (AD DS) can be used to reserve a name for a single user or computer.” DHCP Step-by-Step Guide: Demonstrate DHCP Name Protection“Name squatting occurs when a non-Windows-based computer registers in Domain Name System (DNS) with a name that is already registered to a computer running a Windows® operating system. Please understand, the main thing that scavenging works on is the timestamp.
The use of Name Protection in the Windows Server® 2008 R2 operating system prevents name squatting by non-Windows-based computers. If there is no timestamp, such as a manually created, static record, it will not get scavenged.
This applies to Windows 2000 Professional and all newer operating systems.
With the default settings, a duplicate A record gets registered by DHCP with the client’s new IP.
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. 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.
To configure DHCP Option 081, you must look at the DHCP server properties, under the DNS Tab in DHCP properties. After configuring the above provedure, the credentials and Dns Update Proxy group configuratuion will not update current or delete duplicate records. DHCP will give that duplicate named client an IP, but it will not register it into DNS.