We are experiencing an issue with laptops which move between our wired and wireless networks, and between sites. Each site has its own subnet/dhcp scope, and the sites with wireless have a separate scope for it (one wired and one wireless). The dhcp server is a DC running Windows Server 2003, the server's machine account is in the DNSUpdateProxy security group, and credentials are configured for DNS updates. DHCP lease times are the default 8 days, DNS refresh and norefresh intervals are both 7 days, and scavenging is enabled.
Laptops that change networks get new dhcp addresses on their new subnet, as expected. However, they can change between networks multiple times a day, and in the case of some of our execs who move around the country, can be in multiple offices within one week. The DNS entries for these laptops are not being updated reliably, resulting in problems when our helpdesk has to support them, as they are unable to connect to them by DNS name. We are also in the process of configuring SCCM 2012, and it is causing issues with this as well. There are also multiple DHCP leases for these machines, one per scope they've been in during the last 8 days. I can see from the DHCP logs that DHCP is sending DNS Update Requests for all of these leases, and getting DNS Update Failed.
I've read http://msmvps.com/blogs/acefekay/archive/2009/08/20/dhcp-dynamic-dns-updates-scavenging-static-entries-amp-timestamps-and-the-dnsproxyupdate-group.aspx and a number of other articles and forum posts, but nothing seems to cover this scenario. I've considered lowering the DHCP lease time to a day, and the NoRefresh interval to an hour, with the Refresh interval at 1 day, but I'm not sure what will happen due to the multiple leases. Will these overwrite each other, until they expire? What is the best configuration for this scenario?
Nigel Benfell B.Sc. MCSA