A DHCP reservation ensures a specific device always receives the same IP address from the DHCP server whenever it requests an address. The reservation is typically created by associating the device’s MAC address with a chosen IP address inside the DHCP scope. When that device connects and performs the DHCP process, the server recognizes the MAC address and offers the reserved IP instead of assigning the next available dynamic address. This is commonly used for devices that benefit from consistent addressing (for example, printers, servers, or network appliances) while still centrally managing addressing through DHCP rather than configuring a manual static IP on the endpoint.

An exclusion is the opposite idea: it defines a range of IP addresses within a scope that the DHCP server will not hand out (often because those addresses are used for statically assigned devices). A lease is the time period that a dynamically assigned IP address is valid before it must be renewed; it does not guarantee the same IP every time. A scope is the overall pool/range of IP addresses and DHCP options (gateway, DNS, etc.) available for a given subnet. Therefore, the component that guarantees the same IP is a reservation.