What is a DHCP superscope?
A superscope is an administrative grouping of two or more DHCP scopes on one DHCP server, most often Windows Server. It lets a single server hand out addresses from several IP subnets to clients on the same physical network segment, a setup called a multinet.
Why use a superscope?
- The address pool is running out. When a scope such as 192.168.1.0/24 is nearly full, you can add a second scope (192.168.2.0/24) and group both in a superscope instead of re-addressing the whole network.
- Moving to a new address range. During a renumbering project the old and new scopes run side by side until every client has moved.
- Several logical subnets on one segment. The router interface has an address in each subnet, and the superscope lets the DHCP server answer clients for all of them.
How it works
Each member scope keeps its own address range, exclusions, reservations, lease duration and options such as the default gateway. The superscope has no settings of its own; it only tells the server that these scopes share one physical network. When a DHCPDISCOVER arrives from that segment, the server can offer a lease from any active member scope that still has free addresses.
A superscope does not route traffic. Clients in different subnets of a multinet still need a router, or secondary addresses on the router interface, to talk to each other.
Superscope vs. scope
| Scope | Superscope | |
|---|---|---|
| What it is | One range of addresses for one subnet | A group of scopes on one server |
| Settings | Range, exclusions, reservations, lease time, options | None of its own; each member scope keeps its settings |
| Used for | Normal DHCP on a subnet | Multinets, a full address pool, renumbering |
For the CompTIA A+ exam
Core 1 (220-1201) objective 2.4 covers DHCP scopes, leases, reservations and exclusions. Superscopes aren't named in the objectives, but knowing that a superscope is "a group of scopes" helps you spot it as a distractor when a question is really about a single scope or a reservation.