Border Gateway Protocol (BGP) operates as which type of routing protocol?

Border Gateway Protocol (BGP) is best classified as a path vector protocol. This classification is crucial because BGP is designed to facilitate the exchange of routing information between different autonomous systems (AS), unlike typical distance vector or link-state algorithms, which primarily function within a single AS.

In a path vector protocol like BGP, the primary metric used for routing decisions is the complete path of ASs that a route passes through, allowing the protocol to effectively prevent routing loops and manage policy-based routing decisions across multiple ASs. Each BGP update message carries not only the destination network but also the sequence of ASs that a route traverses, thus providing a more comprehensive understanding of the route's origin and potential paths.

While BGP shares some similarities with distance vector methods, such as maintaining a table of routes and exchanging updates based on changes in the network, it does not simply calculate shortest paths based on distance or hop count. Instead, it focuses on the overall policy for route selection, which can involve a variety of criteria beyond distance, making it unique in its approach to inter-domain routing.

The other options do not accurately describe BGP's functionality. Link state protocols like OSPF and IS-IS operate within a single AS and use a