Introducing OSPF Flashcards
Which three dynamic routing protocols are considered classless? (Choose three.)
A. IS-IS
B. RIP
C. IGRP
D. RIPv2
E. EIGRP
A. IS-IS
D. RIPv2
E. EIGRP
The correct answers are “IS-IS,” “EIGRP,” and “RIPv2.” All three routing protocols transmit the subnet mask in route updates.
Which route is preferred by a router when the router is comparing them using default administrative distances?
A. internal BGP
B. OSPF
C. EIGRP
D. connected
D. connected
The correct answer is “connected.” A connected route has the lowest administrative distance.
Which option a key feature of link-state routing protocols?
A. They are scalable.
B. The convergence takes a lot of time.
C. Updates are only sent periodically.
D. Routers have partial knowledge of the topology.
A. They are scalable.
What is the name between routers running a link-state routing protocol in the same area?
A. topology database
B. neighbor table
C. routing table
D. switching table
A. topology database
Which option regarding OSPF is true?
A. When implementing OSPF only one area can be used.
B. Routers in the same OSPF area have different LSDBs.
C. A router resends its own LSAs every 30 seconds by default as a periodic update.
D. A router creates a neighbor relationship by exchanging hello packets.
D. A router creates a neighbor relationship by exchanging hello packets.
The correct answer is “A router creates a neighbor relationship by exchanging hello packets.” OSPF does not exchange routing information periodically, like distance vector protocols do, but only when there are changes. Moreover, a router floods its own LSAs every 30 minutes by default as a periodic update for synchronization purposes with the other routers in the area. The messages are exchanged among the routers in the same area. Routers in one area build an LSDB based on exchanged messages and have the same LSDBs. One of the advantages of OSPF is that it can be used to build hierarchical routing domains, using multiple areas.
Which OSPF hello packet information must be different, for OSPF neighbor relationship to be formed between two routers?
A. router ID
B. hello and dead intervals
C. area ID
D. router priority
A. router ID
The correct answer is “router ID.” The OSPF router ID uniquely identifies the router. If two routers have the same identification, they will not form OSPF neighbor relationship.
What is a state of the OSPF neighbor relationship after a router becomes active on the link and receives an OSPF hello packet with its own OSPF router ID?
A. down state
B. INIT state
C. two-way state
D. exstart state
C. two-way state
The correct answer is “two-way state.” The two-way state is attained when the router receiving the hello packet sees its own Router ID within the received hello packet’s neighbor field.
On Cisco devices, what is the OSPF cost metric calculation based on?
A. the bandwidth of the link
B. the distance of the link
C. both the bandwidth and the distance of the link
D. the root state of the link
A. the bandwidth of the link
Which packet is used to ensure a reliable transport and a reliable exchange of information?
A. LSAck packet
B. DBD packet
C. LSR packet
D. LSU packet
A. LSAck packet
Which command enables OSPF Area 0 on the interface that is configured with the IPv4 address 172.16.10.1 and the subnet mask 255.255.255.252?
A. network 172.16.10.0 4.0.0.0 area 0
B. network 172.16.10.1 0.0.0.3 area 0
C. network 172.16.10.1 4.255.255.255 area 0
D. network 172.16.10.4 0.0.0.3 area 0
B. network 172.16.10.1 0.0.0.3 area 0
The correct answer is “network 172.16.10.1 0.0.0.3 area 0.” The network command identifies which IP networks on the router are part of the OSPF network. The network that is identified in the network command does not tell the router which network to advertise; instead, it indicates the interfaces on which OSPF will be enabled.
Which command displays information about OSPF timers?
A. show ip ospf neighbor
B. show ip route
C. show ip ospf interface interface-id
D. show ip protocols
D. show ip protocols
The correct answer is “show ip ospf interface interface-id.” The show ip ospf neighbors command displays information about known neighbor OSPF routers. The show ip protocols command displays basic settings of all IPv4 outing protocols configured on a device. The show ip route command displays the routing table.
What is the purpose of link-state advertisements?
A. constructing a topological database
B. specifying the cost to reach a destination
C. determining the best path to a destination
D. verifying that a neighbor is still functioning
A. constructing a topological database
Related to OSPFv3, which of the following statements is correct?
A. OSPFv3 was created specifically to support IPv6.
B. OSPFv3 is compatible with OSPFv2.
C. OSPFv3 does not use multicast addresses.
D. OSPFv3 uses the same LSAs as OSPFv2.
A. OSPFv3 was created specifically to support IPv6.
Which two data structures do the link-state routing protocols use? (Choose two.)
A. LSU database
B. neighbors database
C. link-state interfaces database
D. topology database
E. next-hop database
B. neighbors database
D. topology database
How do link-state protocols limit the scope of route changes?
A. by supporting classless addressing
B. by sending the mask along with the address
C. by sending only updates of a topology change
D. by segmenting the network into areas
C. by sending only updates of a topology change
