Dynamic Host Configuration Protocol (DHCP)

How the IP address gets changed after a period of time.

goal: host dynamically obtains IP address from network server when it
“joins” network (plug and play)

• can renew its lease on address in use
• allows reuse of addresses (only holds address while connected/on)
• support for users who join/leave network

DHCP overview: a client server protocol using UDP, a network function implemented as an application protocol !!!

• host broadcasts DHCP discover msg
• DHCP server responds with DHCP offer msg
• host requests IP address: DHCP request msg
• DHCP server sends address: DHCP ack msg

It will return more than just allocated IP address on subnet.

• address of first-hop router for client
• name and IP address of DNS server
• address prefix (indicating network versus host portion of address)

DHCP is a network function implemented as an application protocol (on top of UDP)