Following are some links that describe DNS scavenging, it's relationship with DHCP, and how to enable it - this is often the cause of stale records:
http://blogs.technet.com/b/ networking/archive/2009/02/09/ optimizing-your-network-to- keep-your-dns-squeaky-clean. aspx
http://blogs.technet.com/b/ networking/archive/2008/03/19/ don-t-be-afraid-of-dns- scavenging-just-be-patient. aspx
http://blogs.technet.com/b/ askpfe/archive/2011/06/03/how- dns-scavenging-and-the-dhcp- lease-duration-relate.aspx
http://technet.microsoft.com/ en-us/library/cc755716(v=ws. 10).aspx
http://blogs.technet.com/b/
http://blogs.technet.com/b/
http://blogs.technet.com/b/
http://technet.microsoft.com/