Wednesday, 15 January 2014

QUESTIONS AND ANSWERS (CCNA Part-5)

1. What algorithm does OSPF use to compute its route table?
A: OSPF uses the shortest path first (SPF) algorithm, which is also known as the Dijkstra algorithm.
2. What three tables does an OSPF router build?
A: OSPF routers build an adjacencies database, a link-state or topological database, and a route table.
3. What is the significance of the DR and BDR?
A: A DR, or Designated Router, serves as a point of contact for an OSPF router on a multiaccess  network, because the DR is responsible for collecting routing updates from routers on the link and distributing these updates to all other routers on the link. If the DR goes offline, the BDR, or Backup Designated Router, takes over the DR’s functions.
4. How are the DR and BDR selected?
A: The DR and BDR are selected based on router priority. If there is a tie, the router with the highest router ID is preferred.
5. How is the router ID determined?
A: The router ID is the highest IP address configured on any of the router’s loopback interfaces. If no loopback interface is configured on the router, the router ID is the highest IP address configured on any of the router’s physical interfaces.
6. What is an ABR?
A: An ABR, Area Border Router, is a router with interfaces that connect to more than one area.
7. What is an ASBR?
A: An ASBR, Autonomous System Boundary Router, is a router with interfaces that connect to more than one autonomous system.
8. What is a stub area?
A: A stub area is an area that does not accept routing updates from outside its autonomous system.
9. What is a totally stubby area?
A: A totally stubby area is an area that does not accept routing updates from outside its area.
10. What is a virtual link?
A: A virtual link logically connects an ABR that does not physically connect the backbone Area 0 to another ABR that does connect to the backbone area, thereby linking an entire area to the backbone area.
Enjoy With this Questions and Answers.

Tuesday, 14 January 2014

QUESTIONS AND ANSWERS ( CCNA -Part-4 )

QUESTIONS AND ANSWERS
1. How does Split Horizon work?
A: A router does not advertise a route back in the direction from which it was
received.
2. How does Poison Reverse work?
A: A router advertises a route as unreachable in the direction from which it was
received.
3. What type of routing protocol maintains neighbors?
A: Link State.
4. When does a distance vector send out routing table updates?
A: At a scheduled time interval.
5. What are the most common Link State routing protocols?
A: OSPF, NLSP, and IS-IS.
6. What type of routing protocol is EIGRP?
A: Hybrid.
7. What is the command to send all traffic destined for 10.2.2.0/24 to router
10.1.1.1/24?
A: ip route 10.2.2.0 255.255.255.0 10.1.1.1
8. What command can be added to a static route to make sure it stays in the routing
table even if its associated interface goes down?
A: permanent
9. What is the administrative distance of OSPF?
A: 110
10. What is the range of values for administrative distance?
A: 0–255