The TCP/IP Guide  9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)       9  TCP/IP Network Configuration and Management Protocols (BOOTP, DHCP, SNMP and RMON)            9  Host Configuration and TCP/IP Host Configuration Protocols (BOOTP and DHCP)                 9  TCP/IP Dynamic Host Configuration Protocol (DHCP)                      9  DHCP Address Assignment and Dynamic Address Allocation and Management

DHCP Lease "Life Cycle" Overview (Allocation, Reallocation, Renewal, Rebinding and Release) and Lease Timers 1 2 3 4 DHCP Configuration and Operation

Lease Address Ranges (Scopes)

In its simplest form, the address pool takes the form of a list of all addresses that the DHCP server has reserved for dynamic client allocation. Along with each address, the server stores certain parameters, such as a default lease length for the address and other configuration information to be sent to the client when it is assigned that address (for example, a subnet mask and the address of a default router). All of this data is stored in a special database on the server.

Of course, many clients will request addresses from this pool. Most of these clients are “equals” as far as the DHCP server is concerned, and it doesn't matter which address each individual client gets. This means most of the information stored with each of the addresses in a pool may be the same except for the address number itself. Due to this similarity, it would be inefficient to have to specify each address and its parameters individually. Instead, a range of addresses is normally handled as a single group defined for a particular network or subnet. These are not given any particular name in the DHCP standards, but are commonly called scopes. This term has been popularized by Microsoft in its DHCP server implementations. Other operating systems sometimes just call these blocks of addresses ranges, but I prefer “scope” so that is what I am using here.

DHCP Lease "Life Cycle" Overview (Allocation, Reallocation, Renewal, Rebinding and Release) and Lease Timers 1 2 3 4 DHCP Configuration and Operation