After DR and BDR are elected, neighbor routers form master-slave relationships to establish the exchange of link-state information. Which OSPF neighbor state describes this phase?

After DR and BDR are elected, neighbor routers form master-slave relationships to establish the exchange of link-state information. Which OSPF neighbor state describes this phase?

• A. Down
• B. Init
• C. ExStart
• D. Exchange

Answer: (C)

In OSPF, the neighbor state where two routers decide which will be the master and which will be the slave, and begin negotiating how to exchange database information, is the phase that starts the actual synchronization of link-state data. This phase, ExStart, sets up the master/slave relationship and launches the exchange of Database Description packets (and MTU negotiation) to prepare for full database synchronization. After this, the routers move into the Exchange phase to continue exchanging DD packets and LSAs. Other states are transitional steps before this: Down means no Hello has been received yet; Init means a Hello was received but neighbor adjacency hasn’t formed; 2-Way means bidirectional communication is established but full adjacency isn’t yet formed; Exchange is the subsequent phase where actual DD packets are exchanged after the master/slave setup.

In OSPF, the neighbor state where two routers decide which will be the master and which will be the slave, and begin negotiating how to exchange database information, is the phase that starts the actual synchronization of link-state data. This phase, ExStart, sets up the master/slave relationship and launches the exchange of Database Description packets (and MTU negotiation) to prepare for full database synchronization. After this, the routers move into the Exchange phase to continue exchanging DD packets and LSAs.

Other states are transitional steps before this: Down means no Hello has been received yet; Init means a Hello was received but neighbor adjacency hasn’t formed; 2-Way means bidirectional communication is established but full adjacency isn’t yet formed; Exchange is the subsequent phase where actual DD packets are exchanged after the master/slave setup.