QUESTION 91
What information does a router running a link-state protocol use to build and maintain its topological database? (Choose two)

A.    hello packets
B.    SAP messages sent by other routers
C.    LSAs from other routers
D.    beacons received on point-to-point links
E.     routing tables received from other link-state routers
F.      TTL packets from designated routers

Answer: AC

QUESTION 92
ROUTER# show ip route
192.168.12.0/24 is variably subnetted, 9 subnets, 3 masks
C 192.168.12.64 /28 is directly connected, Loopback1
C 192.168.12.32 /28 is directly connected, Ethernet0
C 192.168.12.48 /28 is directly connected, Loopback0
O 192.168.12.236 /30 [110/128] via 192.168.12.233, 00:35:36, Serial0
C 192.168.12.232 /30 is directly connected, Serial0
O 192.168.12.245 /30 [110/782] via 192.168.12.233, 00:35:36, Serial0
O 192.168.12.240 /30 [110/128] via 192.168.12.233, 00:35:36, Serial0
O 192.168.12.253 /30 [110/782] via 192.168.12.233, 00:35:37, Serial0
O 192.168.12.249 /30 [110/782] via 192.168.12.233, 00:35:37, Serial0
O 192.168.12.240/30 [110/128] via 192.168.12.233, 00:35:36, Serial 0
To what does the 128 refer to in the router output above?

A.    OSPF cost
B.    OSPF priority
C.    OSPF hop count
D.    OSPF ID number
E.     OSPF administrative distance

Answer: A
Explanation:
The first parameter is the Administrative Distance of OSPF (110) while the second parameter is the cost of OSPF.

QUESTION 93
Which of the following describe the process identifier that is used to run OSPF on a router? (Choose two)

A.    It is locally significant.
B.    It is globally significant.
C.    It is needed to identify a unique instance of an OSPF database.
D.    It is an optional parameter required only if multiple OSPF processes are running on the router.
E.    All routers in the same OSPF area must have the same process ID if they are to exchange routing information.

Answer: AC

QUESTION 94
Open Shortest Path First (OSPF) is a routing protocol developed for Internet Protocol (IP) networks by the Interior Gateway Protocol (IGP) working group of the Internet Engineering Task Force (IETF). What is the default administrative distance of the OSPF routing protocol?

A.    90
B.    100
C.    110
D.    20
E.    130
F.    170

Answer: C

QUESTION 95
Which address are OSPF hello packets addressed to on point-to-point networks?

A.    224.0.0.5
B.    172.16.0.1
C.    192.168.0.5
D.    223.0.0.1
E.    254.255.255.255

Answer: A

QUESTION 96
Which statements describe the routing protocol OSPF? (Choose three)

A.    It supports VLSM.
B.    It is used to route between autonomous systems.
C.    It confines network instability to one area of the network.
D.    It increases routing overhead on the network.
E.    It allows extensive control of routing updates.
F.    It is simpler to configure than RIP v2.

Answer: ACE
Explanation:
The OSPF protocol is based on link-state technology, which is a departure from the Bellman-Ford vector based algorithms used in traditional Internet routing protocols such as RIP. OSPF has introduced new concepts such as authentication of routing updates, Variable Length Subnet Masks (VLSM), route summarization, and so forth.
OSPF uses flooding to exchange link-state updates between routers. Any change in routing information is flooded to all routers in the network. Areas are introduced to put a boundary on the explosion of link-state updates. Flooding and calculation of the Dijkstra algorithm on a router is limited to changes within an area.

QUESTION 97
Which parameter or parameters are used to calculate OSPF cost in Cisco routers?

A.    Bandwidth
B.    Bandwidth and Delay
C.    Bandwidth, Delay, and MTU
D.    Bandwidth, MTU, Reliability, Delay, and Load

Answer: A
Explanation:
The well-known formula to calculate OSPF cost is Cost = 108 / Bandwidth

QUESTION 98
Why do large OSPF networks use a hierarchical design? (Choose three.)

A.    to decrease latency by increasing bandwidth
B.    to reduce routing overhead
C.    to speed up convergence
D.    to confine network instability to single areas of the network
E.    to reduce the complexity of router configuration
F.    to lower costs by replacing routers with distribution layer switches

Answer: BCD
Explanation:
OSPF implements a two-tier hierarchical routing model that uses a core or backbone tier known as area zero (0). Attached to that backbone via area border routers (ABRs) are a number of secondary tier areas. The hierarchical approach is used to achieve the following:
– Rapid convergence because of link and/or switch failures
– Deterministic traffic recovery
– Scalable and manageable routing hierarchy, reduced routing overhead.

Explanation:
To form an adjacency (become neighbor), router A & B must have the same Hello interval, Dead interval and AREA numbers

QUESTION 99
A router has learned three possible routes that could be used to reach a destination network. One route is from EIGRP and has a composite metric of 20514560. Another route is from OSPF with a metric of 782. The last is from RIPv2 and has a metric of 4. Which route or routes will the router install in the routing table?

A.    the OSPF route
B.    the EIGRP route
C.    the RIPv2 route
D.    all three routes
E.    the OSPF and RIPv2 routes

Answer: B
Explanation:
When one route is advertised by more than one routing protocol, the router will choose to use the routing protocol which has lowest Administrative Distance. The Administrative Distances of popular routing protocols are listed below:

QUESTION 100
Which command is used to display the collection of OSPF link states?

A.    show ip ospf link-state
B.    show ip ospf lsa database
C.    show ip ospf neighbors
D.    show ip ospf database

Answer: D
Explanation:
The “show ip ospf database” command displays the link states. Here is an example:
Here is the lsa database on R2.

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