Which Path-Vector Routing Protocol Connects Branch Offices with Redundancy?

Path vector is the deciding constraint The question asks for a routing protocol that connects multiple branch offices, provides automatic load balancing and redundancy, and uses path-vector routing. BGP is the only option that satisfies the path-vector requirement: it advertises reachability with an AS-path and uses path attributes to select and propagate routes. A community explanation summarized this accurately, noting that BGP maintains AS-path information for routing decisions, redundancy, and load balancing across multiple connections or branch offices. BGP can be deployed as eBGP between branch sites or between branches and a provider, and multipath support lets eligible paths be installed for load sharing. Its default behavior is best-path selection, so the load-balancing claim should be read as BGP's capability with appropriate multipath configuration—not as automatic equal-cost behavior on every router.

Why the other options fail A (RIP) is a distance-vector protocol and uses hop count, not an AS-path. B (OSPF) is a link-state interior gateway protocol; it does provide redundancy and equal-cost multipath inside an area, which makes it an attractive trap, but it is not path vector. D (MPLS) is a label-switching forwarding technology, not a path-vector routing protocol. The exam explicitly narrows the answer by protocol category, so feature overlap in OSPF cannot override that constraint. If the scenario dropped “path vector” and described a single enterprise autonomous system with equal-cost links, OSPF would become a viable answer; if it described service-provider label forwarding, MPLS would be relevant. That adjacent decision—category first, features second—is exactly what this question tests.

Operational consequence Choosing OSPF solely because it supports redundancy and load balancing misses the design requirement and can produce an interior-only routing design that does not scale across separate administrative domains. BGP gives policy control through AS-path, local preference, and multi-exit discriminator, but those knobs must be planned; otherwise traffic may not balance as intended. The safe exam takeaway is to identify the named routing family before comparing capabilities, making C the clear answer.