Windows DHCP-Client shall not send UID

So basically you want your client to send their hostname to your DNS server ?

This works great with Windows clients, but for Linux machines, I would go the other way around : set your clients to ask the DHCP server for an IP and a hostname. Using the "request host-name" option, dhclient asks the DHCP server to send a hostname along with the IP address, then sets the hostname of the VM.

Of course you'll need to prepare, in your DNS, a hostname for each IP address in the DHCP range.

This way you don't have the DNS cache / propagation delay problem, and you may have a central place with all the IP and hostnames - your DNS server.

I don't know wether your appliance's DHCP server supports sending hostnames - most does, but I think that's the easiest way for Linux clients.

Note: If you configured your DHCP server so that the same machine always get the same IP address (e.g. using mac address) then it will, obviously, always get the same hostname too. On some DHCP server, you can use directly hostname instead of IP address in the config files.

For Windows DHCP server:

Lease Duration: Required to specify the duration for which address assignments are good. If the Unlimited box is checked, then address assignments never expire; otherwise, specify the lease duration in number of days, hours, and minutes in the Limited To section.

This is as much support for Automatic DHCP allocation as you can get out of Windows DHCP server.

However, odd network problems can occur in an automatic DHCP network if you don't fully understand the consequences. Think carefully about the various scenarios that can occur (server down while client powers on, for instance). For this and other reasons, Automatic is rarely a good choice.