What is DHCP?
How does a device know what IP address it should use when it connects to a new Wi-Fi network? DHCP is the Dynamic Host Configuration Protocol. It is a protocol that lets a device ask the network for an IP address and other configuration data.is.
- DHCP is the Dynamic Host Configuration Protocol. It is the protocol that devices use to get an IPv4 address when they join a network.
- DHCP can also give the device other important configuration information, like the IP address of the server that will research – resolve – DNS answers, and the server that will give the time.
- IPv4 addresses assigned by DHCP will be reclaimed by the DHCP server for another device if the temporary address lease is not renewed. Leases can be very short in places like airports where devices only connect for a few minutes and multiple days in corporate networks where devices might stay in place for years at a time.
If the network has a DHCP server and enough addresses, the server will give the device an address for a defined period. This is called a lease. Leases can be very short in places where people don’t stay long, like train stations and airports. In a home environment a lease might be several days.
The DHCP server can also tell the device about the DNS resolvers it should use. DNS resolvers are the servers that research DNS answers for devices on the network. For instance, a DNS resolver might get the IP address for ipv4.global and tell a device that it is 23.185.0.4.
The DHCP server can also tell the device where to get the time from. Accurate time is not just convenient. The cryptographic protocols used for most transactions rely on accurate time. Without it, users can be subject to replay attacks. So, knowing which time server to use is important for network security.