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I am trying to add two scopes of different range say (192.168.0.5-192.168.0.10), (192.168.0.15-192.168.0.25) on windows DHCP server while I am trying to add the second scope it says the address range and mask conflicts with the existing scope is this valid? do we need to enable any setting to support multiple scopes within the same subnet?

Dave M
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vincity _sportia_taymodaimo
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2 Answers2

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You (usually) can only have one DHCP server per subnet. Think about the IP distribution: a client in your subnet sends a DHCPDISCOVER to broadcast 192.168.0.255. Which of your two DHCP servers should answer?

You should use the complete subnet and add an exclusion for your ranges, e.g. 192.168.0.11-192.168.0.14, or split your network into smaller subnets.

Lenniey
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  • *You (usually) can only have one DHCP server per subnet.*. Disagree. You can have as many DHCP servers listening on a subnet as you like (https://serverfault.com/questions/368512/can-i-have-multiple-dhcp-servers-on-one-network). Whether or not that's a good idea for what the OP is trying to do is debatable, of course, but there's no technical reason not to. I do agree with the rest of what you're saying, what the OP is doing is sub-optimal and they should create one range with exclusions as you suggest. – Rob Moir Jan 15 '19 at 12:47
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    I considered adding **Windows** DHCP server per subnet, because Windows will actively forbid it **on the same server**. If you plan and deploy your servers differently, it's possible to add more servers, but OP asks to add two scopes to the same server in the same subnet, which is not possible. Split-scope needs two different machines AFAIK. – Lenniey Jan 15 '19 at 13:02
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Your issue is that you're creating two scopes that overlap, e.g. you're probably specifying the two scopes with the same /24 subnet mask, which means the address ranges overlap even if the addresses in the scopes do not.

You should be able to create 192.168.0.1/24 and 192.168.1.1/24 as ranges because there is no overlap.

The answer, as Lenniey suggests, is to create one scope and add the address ranges you do not wish to manage via DHCP to the exclusion range for that address pool.

Rob Moir
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