AN Lesson-8

Analyzing DHCP Traffic

Q.   Discuss the stages of a DHCP lease and process with a suitable diagram.

 

DHCP lease

• DHCP clients use two different processes to communicate with DHCP servers and obtain a configuration.
• The initialization process occurs when a client computer first starts and attempts to join the network.
•  The renewal process occurs after a client has a lease but needs to renew that lease with the server.

The Lease Process

The first time a DHCP-enabled client starts, it automatically engages the following initialization process to obtain a lease from a DHCP server:

1. The DHCP client broadcasts a DHCP Discover message to the local subnet.
2. A DHCP server can respond with a DHCP Offer message that contains an offered IP address for lease to the client.
3. If the client is running a version of Windows earlier than Windows 2000, or if no static alternate address has been provided and IP autoconfiguration has been disabled, the client fails to initialize. If left running, it continues to resend DHCP Discover messages (4 times every 5 minutes) until it receives a DHCP Offer message from a server.
4. As soon as a DHCP Offer message is received, the client selects the offered address by replying to the server with a DHCP Request message.