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Limitations Creating DHCP Reservations

This article was previously published under Q196066
This article has been archived. It is offered "as is" and will no longer be updated.
DHCP manager allows certain DHCP reservations outside the DHCP scoperange but denies them if they are outside the subnet range. Several rulesmust apply when creating reservations.
The DHCP server must service the subnet where the reservation is beingcreated.

These three rules guide you in creating reservations:
  1. You may create a reservation in any scope range.

    This can include Excluded ranges.
  2. You may create a reservation in a subnet range even if the reservation falls outside the actual scope Start and End addresses for that subnet.
  3. You cannot create reservations outside the subnet range of any of your existing scopes.
As a simple example, take a DHCP server that has no existing scopes:
  • Let's say you have a standard Class C subnet for with mask
  • You can create a scope for the first half of the subnet so that the scope has a starting address of and an ending address of
  • You can now create a reservation for the address (Rule 1)
  • You can also create a reservation that lies outside the scope but still lies in the subnet range.

    For example, reserve (Rule 2)
  • You cannot create a reservation for the address, which lies outside the subnet of any existing scope. (Rule 3)

Article ID: 196066 - Last Review: 12/05/2015 09:47:37 - Revision: 1.2

Microsoft Windows 2000 Server, Microsoft Windows 2000 Advanced Server, Microsoft Windows NT Server 4.0 Standard Edition, Microsoft Windows NT Server 4.0 Enterprise Edition

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