DHCP reservation precedence over exclusion

[richard]

DHCP server on Win 2000 Server sp4:

I've noticed that if I create a reservation within part of an address
pool that is excluded, then the DHCP server hands out that address to
the client correctly. For example:

Address pool: 10.2.0.100 -> 10.2.0.200
Exclusion range: 10.2.0.150 -> 10.2.0.200
Reservation: 10.2.0.180

When the client for whom the reservation is intended boots, it gets
given its intended address, despite the fact that it's within an
excluded range. So reserved addresses take precedence over exclusions.

Is this a safe thing to do? If it works without problem,it would be
very useful to me.

Richard

 

[Michael D. Ober]

This is actually far better and easier to manage than the opposite method,
which NT4 used. Putting the reservations in non-Excluded ranges is
difficult to manage simply because the DHCP server is multi-threaded with
the DHCP management GUI only one of the possible assignment threads.
Consider a reservation to be a DHCP assignment. The question is who gets
priority to the address - the GUI reservation dialog which may or may not
have an address keyed in yet or the client that's booting and requesting an
address. By putting the reservations in an "excluded" range, this issue
completely disappears.

Mike Ober.

 

[richard]

The question is who gets
priority to the address - the GUI reservation dialog which may or may not
have an address keyed in yet or the client that's booting and requesting an
address. By putting the reservations in an "excluded" range, this issue
completely disappears.

Exactly.

I glad it works that way, it makes life easier. I was concerned that I
was exploiting some bad behaviour that wouldn't behave that way
consistently. The docs I've seen don't mention the ability to do this.

regards
Richard