Which of the following best describes an Exterior Gateway Protocol?

An Exterior Gateway Protocol (EGP) is specifically designed to facilitate the exchange of routing information between different autonomous systems (AS). Autonomous systems represent networks or groups of networks that are under the control of a single organization and present a common routing policy.

Using an EGP, such as the Border Gateway Protocol (BGP), networks can share route information with other networks, enabling them to make informed decisions about the best paths for data transmission across multiple distinct networks. This communication is essential for maintaining efficient routing across the internet, which consists of numerous interconnected autonomous systems.

The other options don't accurately define an EGP. For instance, protocols used only within an organization's IP network typically refer to Interior Gateway Protocols (IGPs), which operate internally rather than between autonomous systems. Similarly, optimizing bandwidth and automatically adjusting routes pertains more to the role of routing protocols in local scenarios rather than the definitions of EGPs, which deal primarily with inter-domain routing.