Which of these is an essential function of a routing protocol?

The essential function of a routing protocol is to exchange routing information between routers. This process allows routers to share information about network topology and the best paths to reach specific destinations within the network. By doing this, the routing protocol helps in maintaining accurate and up-to-date routing tables, which are crucial for ensuring efficient and reliable data transmission across the network.

Routing protocols, such as OSPF, BGP, and EIGRP, enable routers to communicate with one another about their known networks and available routes. This exchange of information is fundamental to dynamic routing, allowing the network to adapt to changes such as route failures, topology changes, or the addition of new routes, thus ensuring optimal data routing.

The other options, while related to network functionality, do not represent essential functions of a routing protocol. Assigning IP addresses is the responsibility of a DHCP service, creating subnets pertains to network design and allocation of address space, and providing DHCP services is about IP address management for clients rather than routing decisions.