Computer Networks Questions & Answers – OSPF Configuration MCQ أسئله شبكات بالأجابات الجزء الثاني و الستون

Computer Networks Questions & Answers – OSPF Configuration

1. An OSPF router receives an LSA, the router checks its sequence number, and this
number matches the sequence number of the LSA that the receiving router already has.
What does the receiving router do with the LSA?
a) Ignores the LSA
b) Adds it to the database
c) Sends newer LSU update to source router
d) Floods the LSA to the other routers

Answer: a
Explanation: An OSPF router receives an LSA, the router checks its sequence number, and this number matches the sequence number of the LSA that the receiving router already has Ignores the LSA.

2. An OSPF router receives an LSA. The router checks its sequence number and finds that
this number is higher than the sequence number it already has. Which two tasks does
the router perform with the LSA?
a) Ignores the LSA
b) Adds it to the database
c) Sends newer LSU update to source router
d) Floods the LSA to the other routers

Answer: b
Explanation: An OSPF router receives an LSA. The router checks its sequence number and finds that this number is higher than the sequence number Adds it to the database, Floods the LSA to the other routers.

3. An OSPF router receives an LSA. The router checks its sequence number and finds that
this number is lower than the sequence number it already has. What does the router do
with the LSA?
a) ignores the LSA
b) adds it to the database
c) sends newer LSU update to source router
d) floods the LSA to the other routers

Answer: c
Explanation: An OSPF router receives an LSA. The router checks its sequence number and finds that this number is lower than the sequence number sends newer LSU update to source router.

4. Each LSA has its own age timer. By default, how long does an LSA wait before requiring an update?
a) 30 seconds
b) 1 minute
c) 30 minutes
d) 1 hour

Answer: c
Explanation: Each LSA has its own age timer. By default, 30 minutes does an LSA wait before requiring an update.

5. Distance vector protocols use the concept of split horizon, but link-state routing protocols, such as OSPF, do not.
a) True
b) False

Answer: b
Explanation: Distance vector protocols use the concept of split horizon, but link-state routing protocols, such as OSPF, do not use this.

6. The outcome of Dijkstra’s calculation is used to populate the __________
a) Topology table
b) Routing table
c) Neighbor table
d) Adjacency table

Answer: b
Explanation: The outcome of Dijkstra’s calculation is used to populate the Routing table.

7. What is the IP protocol number for OSPF packets?
a) 89
b) 86
c) 20
d) 76

Answer: a
Explanation: 89 is the IP protocol number for OSPF packets.

8. Which packet is NOT an OSPF packet type?
a) LSU
b) LSR
c) DBD
d) Query

Answer: d
Explanation: Query packet is NOT an OSPF packet type.

9. Which multicast address does the OSPF Hello protocol use?
a) 224.0.0.5
b) 224.0.0.6
c) 224.0.0.7
d) 224.0.0.8

Answer: a
Explanation: 224.0.0.5 is the multicast address does the OSPF Hello protocol use.

10. The Hello protocol sends periodic updates to ensure that a neighbor relationship is maintained between adjacent routers.
a) True
b) False

Answer: a
Explanation: The Hello protocol sends periodic updates to ensure that a neighbor relationship is maintained between adjacent routers.

11. DBD packets are involved during which two states?
a) Exstart
b) Loading
c) Exchange
d) Two-way

Answer: a
Explanation: DBD packets are involved during which two states Exstart, Exchange.

12. At which interval does OSPF refresh LSAs?
a) 10 seconds
b) 30 seconds
c) 30 minutes
d) 1 hour

Answer: d
Explanation: None.

13. Which field is NOT a field within an OSPF packet header?
a) Packet length
b) Router ID
c) Authentication type
d) Maxage time

Answer: d
Explanation: Maxage timeis NOT a field within an OSPF packet header.

14. Which two commands are required for basic OSPF configuration?
a) Network ip-address mask area area-id
b) Network ip-address wildcard-mask area area-id
c) Router ospf process-id
d) both Network ip-address wildcard-mask area area-id and Router ospf process-id

Answer: d
Explanation: Network ip-address wildcard-mask area area-id, Router ospf process-id are required for basic OSPF configuration.

15. Which OSPF show command describes a list of OSPF adjacencies?
a) Show ipospf interface
b) Show ipospf
c) Show ip route
d) Show ipospf neighbor

Answer: d
Explanation: Show ipospf neighborOSPF show command describes a list of OSPF adjacencies.

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