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.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.
DHCP is set to limit the lease for 5 hours and has dynamic updates according to: Always dynamically update DNS A and PTR records, Discard A and PTR records when lease is deleted. 5 Hours for the no-refresh interval Refresh interval is set to 5 Hours as well.
DHCP is also set to update DNS and PTR records for DHCP clients that do not request updates. Why do I still have DNS records with a timestamp from September.. Are the scavenging settings set on the zone, or did you do the "all zones" setting on the server?
Is the box at the top of that dialog checked to actually enable the scavenging?
Is the "Enable automatic scavenging" box checked in the "Advanced" tab of the DNS server's properties?
Despite it being a DHCP Option, it’s not found in a DHCP server, scope or class option. You must delete them manually to allow DHCP to take care of all new records moving forward. Quoted from the following link: “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.
Also, it will allevaite another issue – If DHCP is on a DC, it will not overwrite the original host record for a machine getting a new lease with an IP previoulsy belonging to another host. The use of Name Protection in the Windows Server® 2008 R2 operating system prevents name squatting by non-Windows-based computers. There are some misconceptions prompting fears that Scavenging will remove everything in your zone, includind servers.
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.
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.
With the default settings, a duplicate A record gets registered by DHCP with the client’s new IP.
This is because the client will not update itself due to the current record in DNS is beyond the lease period.