Which protocol is a link-state routing protocol that uses a cost based on bandwidth and has no hop count limit?

Which protocol is a link-state routing protocol that uses a cost based on bandwidth and has no hop count limit?

• A. BGP
• B. RIP
• C. EIGRP
• D. OSPF

Answer: (D)

Link-state routing protocols build a complete view of the network topology and then choose routes by summing link costs, rather than counting hops. The protocol described uses a cost based on bandwidth, meaning faster links have lower costs, and the path with the lowest total cost is chosen. Since decisions are based on the total cost across the entire path rather than how many routers are traversed, there isn’t a fixed hop-count limit. That combination—topology flooding, a bandwidth-based cost metric, and route calculation via the lowest-cost path—points to Open Shortest Path First. BGP is a path-vector protocol between autonomous systems, not link-state; RIP is a distance-vector protocol that relies on hop count and has a 15-hop limit; EIGRP uses a hybrid metric and isn’t purely link-state.

Link-state routing protocols build a complete view of the network topology and then choose routes by summing link costs, rather than counting hops. The protocol described uses a cost based on bandwidth, meaning faster links have lower costs, and the path with the lowest total cost is chosen. Since decisions are based on the total cost across the entire path rather than how many routers are traversed, there isn’t a fixed hop-count limit. That combination—topology flooding, a bandwidth-based cost metric, and route calculation via the lowest-cost path—points to Open Shortest Path First. BGP is a path-vector protocol between autonomous systems, not link-state; RIP is a distance-vector protocol that relies on hop count and has a 15-hop limit; EIGRP uses a hybrid metric and isn’t purely link-state.