Briefly describe the DHCP renewal rebind and reinitializatio

Briefly describe the DHCP renewal, rebind and reinitialization sequence

Solution

The client DHCP first attempts to renew its lease when 50 percent of the original lease time, known as T₁, has passed. A unicast DHCP Request message is send to the DHCP server that originally granted its lease, is send to the DHCP client at this point of time. If the lease is available and the server is still available, the lease is renewed with a unicast DHCP Ack message as server responded. Suppose the current lease of the client is no longer available, and the original DHCP server is available, the DHCP server responds with a DHCP Nack message, and the client immediately starts the process to obtain a new lease. This can happen if the client has changed subnets or if the DHCP server cannot fulfil the lease request for some other reason.

If the DHCP server is not responding, the client will wait until 87.5 % of the lease time has passed.(known as T₂). At T₂, the client enters into a rebinding state, and a DHCP Request message is broadcasted in attempt to renew the lease from any DHCP server which is available. If by the time lease is going to expire and no DHCP server is available, the client immediately unbinds itself from the existing lease and starts the process to obtain a new lease, beginning with a DHCP Discover message.