dhcp clients & new dhcp server

We're moving our dhcp service off of an NT4 box, onto a 2k or 2k3 server.
I understand how to migrate the data, but have a question about the client
side of the house.
How will our 2K and XP dhcp clients weather the storm? One suggestion was to
turn off all the client PCs, migrate the server and then turn the clients
back on.
This seems a little excessive, as there are over 700 machines in our office.
It seems to me that clients will have their address and when they send out
the dhcp request, they will be granted the same IP. DHCP is smart enough to
understand what IP's are already in use and this is a non issue.

Thoughts and suggestions appreciated

 

The default lease is for 7 or 8 days. Reduce the lease interval to 1 hour
on the NT4 DHCP server, one week in advance of shutting it down. By the
time you take the NT4 server off-line they clients will be renewing every 1
hour and will make the transition to the new DHCP server within an hour of
shutting down the old.

 

Thanks Steve.

One further question: I am unsure if we'll be changing the IP address of the
new DHCP server to match the NT4 machine that we're bringing down. While that
would be ideal for the clients to hit the same machine, if it is a different
IP, DHCP requests will go out to a non-existent address, get no reply, and
then broadcast for a DHCP ack - the new server will then complete the DORA
process and clients will be properly addressed.

This isn't really a question I know, but just wanted to bounce this idea off
you.

Thanks,

E

 

Steve's reply is the best solution.

To answer you second question, DHCP requests are made by a discover
broadcast. You don't configure them to point to a specific server. As long
as the new DHCP server is on the same subnet, your clients won't have a
problem getting a new IP address.