Besides EIGRP, which other IGP protocol supports unequal load-balancing?
- IS-IS
- RIP
- OSPF
- BGP
- None of the above
Explanation: EIGRP is unique among routing protocols because it is the only one that supports both equal and unequal-cost path load balancing.
While other Interior Gateway Protocols (IGPs) like OSPF and RIP support Equal-Cost Multipath (ECMP) load balancing using the maximum-paths command, they do not have a mechanism for balancing traffic across links with different metrics. EIGRP achieves unequal-cost load balancing through the variance command, which allows the router to install feasible successor routes into the routing table if their metric is less than the best metric multiplied by the variance value.
Regarding the other options:
- BGP is an Exterior Gateway Protocol (EGP) and is explicitly described as not being designed to perform load balancing; its selection process eliminates multiple paths until only a single best path remains.
- OSPF and RIP are limited to equal-cost load balancing only.
Consequently, since EIGRP is identified as the unique protocol with this capability, "None of the above" is the correct choice.
Related exam: Modules 8 – 13: Checkpoint Exam: Network Routing Answers (CCNP ENCOR v9)
