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200-301 · Question #753

When a router undergoes the exchange protocol within OSPF, in what order does it pass through each state?

The correct answer is B. exstart state > exchange state > loading state > full state. During OSPF neighbor adjacency formation, routers sequentially pass through the Exstart, Exchange, Loading, and Full states to establish a master/slave relationship, exchange database summaries, request missing link-state advertisements, and achieve full database synchronization.

Submitted by olafpl· Mar 5, 2026IP Connectivity

Question

When a router undergoes the exchange protocol within OSPF, in what order does it pass through each state?

Options

  • Aexstart state > loading state > exchange state > full state
  • Bexstart state > exchange state > loading state > full state
  • Cexstart state > full state > loading state > exchange state
  • Dloading state > exchange state > full state > exstart state

How the community answered

(43 responses)
  • A
    2% (1)
  • B
    95% (41)
  • D
    2% (1)

Why each option

During OSPF neighbor adjacency formation, routers sequentially pass through the Exstart, Exchange, Loading, and Full states to establish a master/slave relationship, exchange database summaries, request missing link-state advertisements, and achieve full database synchronization.

Aexstart state > loading state > exchange state > full state

This order incorrectly places the 'loading state' before the 'exchange state' and 'full state', which is not how OSPF establishes adjacency.

Bexstart state > exchange state > loading state > full stateCorrect

The correct order of OSPF neighbor states for establishing full adjacency is: Exstart (master/slave determination and initial DBD exchange), Exchange (full DBD exchange), Loading (requesting and sending missing LSAs), and finally Full (databases are synchronized).

Cexstart state > full state > loading state > exchange state

This order incorrectly places the 'full state' before the 'loading state' and 'exchange state', which are essential steps to achieve full adjacency.

Dloading state > exchange state > full state > exstart state

This order begins with 'loading state' and places 'exstart state' last, which fundamentally misrepresents the OSPF neighbor state machine process.

Concept tested: OSPF neighbor states adjacency formation

Source: https://www.cisco.com/c/en/us/support/docs/ip/open-shortest-path-first-ospf/13685-1.html

Topics

#OSPF#neighbor states#exchange protocol#LSA flooding

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