Which protocol is primarily used for the automatic assignment of IP addresses?

The protocol primarily used for the automatic assignment of IP addresses is DHCP, which stands for Dynamic Host Configuration Protocol. DHCP allows network administrators to manage and automate the distribution of IP addresses within a network efficiently. This process significantly reduces the manual configuration efforts required for each device that connects to the network.

When a device connects to a network, it sends a request for an IP address to a DHCP server. The server then assigns an available IP address from a predefined range, along with additional network configuration details such as subnet mask, default gateway, and DNS server information. This dynamic allocation simplifies network management and helps in efficiently utilizing the limited IP address space, especially in environments with many devices joined to the network.

The other options listed serve different purposes: DNS translates domain names into IP addresses, ARP resolves IP addresses to MAC addresses to enable communication at the network level, and RIP is a routing protocol used to facilitate the exchange of routing information between routers rather than the allocation of IP addresses.