Which protocol is primarily used for load balancing among multiple routers?

The correct choice, which is GLBP, stands for Gateway Load Balancing Protocol. This protocol is specifically designed for load balancing among multiple routers that share a virtual IP address. GLBP allows multiple routers to participate in the forwarding of packets towards a common virtual IP, which helps in distributing the traffic load across multiple gateways, enhancing redundancy and efficiency in network utilization.

Unlike other protocols listed, which may offer redundancy or failover capabilities, GLBP provides an active-active load balancing feature that enables it to forward packets through multiple active routers simultaneously. Each router participating in GLBP takes turns being the Active Virtual Gateway (AVG) and Active Virtual Forwarders (AVFs) for the virtual IP, thus facilitating effective distribution of traffic.

While VRRP (Virtual Router Redundancy Protocol) and HSRP (Hot Standby Router Protocol) are both designed for redundancy and failover, they do not offer load balancing capabilities; they typically select a single active pathway and allow the backup router to take over only if the primary fails. OSPF (Open Shortest Path First) is primarily a routing protocol used for determining the best paths for data through a network rather than for load balancing among routers serving as gateways. Thus, GLBP serves the specific purpose of