Which Routing Protocol Is Link-State: OSPF vs RIP and BGP
Short answer
B OSPF is the link-state routing protocol because it builds a topology database and runs Dijkstra's SPF algorithm, unlike RIP, BGP, and static routes.
Question
Key Takeaways
The question tests routing-protocol classification, and the main trap is choosing the familiar dynamic protocol BGP even though it is path-vector rather than link-state.
OSPF is the link-state routing protocol in this N10-009 question because it builds a topology map and runs Dijkstra's SPF algorithm; RIP is distance-vector and BGP is path-vector.
Common mistake: Choosing BGP because it is a prominent dynamic routing protocol; BGP is a path-vector exterior gateway protocol, so it does not build a link-state database for SPF calculation.
Expert Analysis
Why BGP is the tempting wrong answer
Option C, BGP, is the most attractive wrong choice because it is a widely deployed dynamic routing protocol and candidates often remember it as the advanced one. It satisfies the surface clue that the answer should be a protocol rather than a static route, but BGP is a path-vector exterior gateway protocol. It exchanges reachability with AS-path attributes and policy decisions; it does not build a link-state database or run Dijkstra's shortest path first calculation.
The defining link-state test
A link-state protocol has each router advertise the state of its links, build a complete topology map for the area, and compute shortest paths with SPF. OSPF, option B, is the textbook example. The supplied comment describes OSPF as a classic link-state protocol that uses Dijkstra's algorithm to calculate shortest paths within an area, which aligns with the question's wording. That is the decisive match.
The other options
Option A, RIP, is a distance-vector protocol that uses hop count; it shares routes with neighbors and does not build a link-state topology. Option D, a static route, is a manually configured entry and not a routing protocol at all. Neither can be the link-state answer.
Verdict
The correct answer is B. OSPF is the only link-state routing protocol listed; BGP is path-vector, RIP is distance-vector, and static routing is not a protocol.
Official Reference
- https://www.rfc-editor.org/rfc/rfc2328
- https://www.rfc-editor.org/rfc/rfc4271
- https://www.rfc-editor.org/rfc/rfc2453
These links open the official vendor documentation in a new tab.
Exam Strategy
When a question asks for a routing-protocol category, first map each option to its algorithm: link-state builds a topology and runs SPF, distance-vector shares full tables with neighbors, path-vector carries AS-path attributes, and static routes are manual entries, not protocols. Eliminate static routes first, then separate RIP, OSPF, and BGP by their category rather than by popularity or administrative distance. For N10-009, memorize one signature fact per protocol; on OSPF questions, the words link-state and Dijkstra/SPF should point to OSPF.
Frequently Asked Questions
Why is BGP not the answer if it is a dynamic routing protocol?
What makes OSPF a link-state protocol?
Is a static route considered a routing protocol?
Discussion 1 contributions
Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.
From public community threads 1
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ERB14 👍 1 Answered BOSPF (Open Shortest Path First): This is a classic link-state routing protocol that uses Dijkstra's algorithm to calculate the shortest path to each node within an area.
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