ccna interview questions pdf free download

ccna interview questions pdf free download.2. Election DR/BDRMultiple access networks usually have multiple routers, in this case, OSPF needs to establish the DR and BDRo DR election is determined using the router ID and priority field values in the Hello packet. The router with the highest priority value becomes the DR and the router with the next highest priority value becomes the BDR. if the priorities are the same, the router with the highest router ID becomes the DR.3. Discovering RoutersThe router and the router first use the router ID information in the Hello packet to confirm the master-slave relationship, and then the master and slave routers exchange link state information digests with each other. Each router analyzes and compares the summary information, and if the received information has new content, the router will request the other party to send the complete link state information. After this state is completed, a FullAdjacency relationship is established between the routers.4. Selecting the appropriate routeWhen a router has a complete link state database, the OSPF router independently computes the optimal path to each destination network using the SPF algorithm based on the contents of the link state database, and stores the path in the routing table. OSPF uses the measure (Cost) to calculate the optimal path to the destination network, and the one with the lowest Cost is the optimal path.5. Maintaining Routing InformationWhen the state of a link changes, OSPF informs other routers on the network through a flooding process. When the OSPF router receives a link state update packet containing the new information, it updates its own link state database and then recalculates the routing table using the SPF algorithm. During the recalculation process, the router continues to use the old routing table until the SPF completes the calculation of the new routing table. New..302.Cisco Networking Lab CCNA Lab Guide (Release 2) Link state information is sent to other routers. It is important to note that OSPF routing information is automatically updated even if the link state has not changed. the default time is 30 minutes. called a link state refresh.17.1.7 OSPFv2 and OSPFv3 Comparison