DHCP not updating DNS...Help?

[devries_m]

I have a problem primarily with laptop users that roam around the building…

They log onto the network on an ethernet cable and DHCP assigns an IP address. Then they connect to wireless (on a different subnet) and pick up a new IP address via DHCP again (all the while staying connected to LAN on ethernet still).

DHCP in the background updates DNS so the entry is current and correct against wireless subnet. The problem is when they disconnect wireless - they are left with the wireless subnet ip configuration but are on wired - uh oh! I have to wade through change management (not that bad for this simple change thank goodness, but it's still a pain nonetheless) to manually delete the DNS entry and recreate properly…

Or better yet: sometimes DHCP is not updating DNS and a user is left with either multiple IP addresses from various other subnets that they have connected to, or an incorrect IP address that just isn't updating...

We have disabled the devices the ability to update their own DNS simply because our server DNS records and workstation DNS records are stored in the same zone/database, etc. - afraid of an unknowing user (or technician) changing a client to a server name and messing up DNS…

I'm wondering…If I crank up lease expiry, will this help? Or should I create separate sub-domains - one for workstations and one for servers and then allow clients to update their own DNS instead of DHCP doing the updating (or rather, supposed to be doing)?

Is there logs other then server\sys\etc that will tell me why DHCP is not updating in certain cases or a way to force DHCP to clear an IP address assignment if it's not reachable (I see the pingable option from DNS/DHCP java console but it doesn't seem to force any different behaviour here…). Will it create too much traffic or load on my server (of course I realize this is proportionate to hardware and other running services so maybe that can't be answered without seeing things first person but a rough idea on perf. Hit would be appreciated).

If I turn on the audit trail and alerts options for servers from DNS/DHCP console - where do I go to review to will it display on console screen (or both)?

md