What is DHCP?

DHCP stands for Dynamic Host Configuration Protocol, which is a network protocol used to automatically assign IP addresses and other network configuration parameters to devices connected to a network. Here's an explanation table for the main components of DHCP:

TermExplanation

DHCP server	A server that manages a pool of IP addresses and assigns them to devices on the network.
DHCP client	A device that connects to a network and requests an IP address and other configuration parameters from a DHCP server.
DHCP lease	The amount of time a DHCP client can use an IP address before it must renew its lease with the DHCP server.
DHCP relay	A device that forwards DHCP requests from clients on one network to a DHCP server on another network.
DHCP reservation	A DHCP server configuration that assigns a specific IP address to a specific device based on its MAC address.

Here's an example of how DHCP works in Ubuntu 18:

1. A device (the DHCP client) connects to the network and sends a broadcast message requesting an IP address.
2. The DHCP server receives the broadcast message and responds with an offer of an IP address from its pool.
3. The DHCP client accepts the offer and sends a request to the DHCP server for the offered IP address.
4. The DHCP server acknowledges the request and assigns the IP address to the DHCP client for a specific lease time.
5. The DHCP client uses the assigned IP address and other configuration parameters to communicate on the network until the lease time expires.
6. The DHCP client must renew its lease with the DHCP server before the lease time expires in order to continue using the assigned IP address.

In Ubuntu 18, the DHCP server can be configured and managed using the "isc-dhcp-server" package, while the DHCP client is built into the operating system and can be configured using the "network-manager" utility.