This is an old revision of the document!
http://www.tomshardware.com/faq/id-1954333/create-reverse-primary-dns-zone-windows-server-2012.html
http://msmvps.com/blogs/acefekay/archive/2009/08/20/dhcp-dynamic-dns-updates-scavenging-static-entries-amp-timestamps-and-the-dnsproxyupdate-group.aspx