IP addresses can be reserved by manually assigning them to particular clients. A reserved address can be associated with a permanent lease or a dynamic lease. When a reserved address is assigned a permanent lease, the following statements are true:
The address can be allocated only to the client that is bound to the address.
The DHCP server cannot allocate the address to another client.
The address cannot be reclaimed by the DHCP server.
If a reserved address is assigned a dynamic lease, the address can be allocated only to the client that is bound to the address. However, the client must track lease time and negotiate for a lease extension as if the address were not reserved. This strategy enables you to track when the client is using the address by looking at the network table.
You cannot create reserved addresses for all the IP addresses during the initial configuration. Reserved addresses are intended to be used sparingly for individual addresses.