The protocol used to assign IP addresses automatically is DHCP, short for Dynamic Host Configuration Protocol. When a device joins a network, a DHCP client requests configuration information from a DHCP server, which can provide an IP address and settings such as a subnet mask, default gateway, and DNS servers.
DHCP normally assigns an address for a limited lease period rather than granting permanent ownership. The device can renew the lease, and the server can later reclaim the address for another client. This approach prevents network administrators from manually configuring every computer, phone, printer, or smart device on a network.
DHCP developed from the earlier Bootstrap Protocol, or BOOTP, and was first defined in 1993. NAT, ARP, and DNS perform different jobs: NAT translates addresses, ARP helps map IP addresses to hardware addresses on local networks, and DNS translates domain names into IP addresses. DHCP can support both IPv4 and IPv6, with DHCPv6 used for IPv6 networks.