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I've been having problems with a few statements I've been reading. When setting up DHCP Reservation based on MAC addresses... Do the reserved IP's need to be in one of the scopes or not?

Judging from what I've seen (not sure if this was correct) it had to be in one of the scopes in order to be reserved.

What would be the correct answer to this?

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What OS are you running the DHCP on? On Windows 2008 R2, you can't define a reservation outside the scope.

On Server 2003, you COULD do it but it's not at all needed in most cases.

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2008 r2... So basically I need the IP-address inside a scope range to be able to reserve it? – Dempsey FoxDie Van Assche May 14 '13 at 8:02
Correct! Are there any specific reasons why you want to reserve an IP outside of the scope? If it's outside all scopes of DHCP servers, it has to be set manually. In that case, there should be some kind of control on what has been taken and what has not! – xstnc May 21 '13 at 10:14

I personally have a linux router, one of these in a box, and DHCP reservation is done in such a way, that if I set DHCP range from e.g. x.x.x.150 to x.x.x.200, and have my laptop be at x.x.x.2, I still get that address from DHCP, even though it isn't in range. So the answer would be NO, you don't have to reserve from range, from my experience.

Also, when setting up reservation, linux router does put this in a NAT table (this is example):

DROP all -- anywhere MAC !00:08:74:F7:4D:69

so that anyone who manually enters someone else's IP to his adapter does not have access to the WAN port.

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If an address is not within a scope, then your DHCP server will not be handing its address out.

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