This document provides answers to questions about CCNA 3 Chapter 6 and OSPF routing. It contains 20 multiple choice questions about OSPF concepts like DR/BDR election, network types, route calculation, and router configuration. Answers are provided for each question to help students learn and test their knowledge of OSPF.

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CCNA 3 Chapter 6 V4.0
Labels: CCNA 3 Chapter 6 V4.0
1
Refer to the exhibit. What statement describes the DR/BDR relationship of the HQ
router?
HQ is the DR.
HQ is the BDR.
HQ is a DROTHER.
HQ is a member of an NBMA network.
2
Which two features are associated with Frame Relay OSPF point-to-multipoint
environments? (Choose two.)
A DR is not elected.
The OSPF priority value determines the active DR on the Frame Relay link.
OSPF neighbor routers are statically defined.
The link types are identified as broadcast multiaccess.
The BDR will have a router ID whose value is greater than the DR router ID.
3

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Refer to the exhibit. How was the OSPF default gateway entry for R2 determined?
Default routes are automatically injected by OSPF into all advertisements.
A static default gateway route is defined in the configuration of R2.
The default-information originate command is applied on R1.
The ISP defines the gateway of last resort and automatically passes it to R1 and R2.
The ip default-gateway command is applied on R2.
4
What is always required for OSPF routers to share routing information?
designated routers
a backup designated router

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neighbor adjacencies
an NBMA network topology
links that are configured on the 224.0.0.0 network
5
Refer to the exhibit. A network administrator has implemented OSPF and the network

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has converged. If all router interfaces are enabled and functional, what route will
OSPF view as lowest cost when moving frames from Host3 to Host1?
R3 to R4 to R1
R3 to R1
R3 to R2 to R1
R3 to R5 to R2 to R1
6
Refer to the exhibit. Which commands configure router A for OSPF?
router ospf 1

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network 192.168.10.0
router ospf 1
network 192.168.10.64 0.0.0.63 area 0
network 192.168.10.192 0.0.0.3 area 0
router ospf 1
network 192.168.10.64 255.255.255.192
network 192.168.10.192 255.255.255.252
router ospf 1
network 192.168.10.0 area 0
7
Refer to the exhibit. Which network statement configures the home router to allow all

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the interfaces to participate in OSPF?
network 10.0.0.0 0.3.255.255 area 0
network 10.8.0.0 0.0.0.3 area 0
network 10.8.0.0 0.3.255.255 area 0
network 10.10.0.0 0.0.0.3 area 0
network 10.12.0.0 0.3.255.255 area 0
8
Which statement is true regarding OSPF DR and BDR elections?
A new DR/BDR election occurs each time a new OSPF neighbor is added.
The router with the highest OSPF priority setting wins the election for DR.
The default priority value for a router connected to a multi-access network is 0.
The router with the highest MAC address is elected as the DR when the default
priority values are used.
9
Refer to the exhibit. The network administrator would like only the 172.16.32.0

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network advertised to Router1. Which OSPF network command accomplishes this?
Router2(config-router)# network 172.16.0.0 0.0.0.15 area 0
Router2(config-router)# network 172.16.0.0 0.0.15.255 area 0
Router2(config-router)# network 172.16.32.0 0.0.15.255 area 0
Router2(config-router)# network 172.16.32.0 0.0.255.255 area 0
10
Which two statements describe the operation of link-state routing protocols? (Choose
two.)
All routers in the same area have identical link-state databases when converged.
Routing loops are prevented by running the Diffusing Update Algorithm (DUAL).
Link-state routers send frequent periodic updates of the entire routing table.
Reliable Transport Protocol (RTP) is used to deliver and receive LSAs.
Calculating the shortest path for each destination is accomplished with the SPF
algorithm.
11

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Refer to the exhibit. Routers A, B, and C are part of the existing OSPF network.
Router D has been added to the network. All routers are running OSPF and have the
indicated priorities applied to the interface. What is the DR/BDR status immediately
after router D is added to the existing network?
An election is forced and router D wins the DR election.
The DR and BDR do not change until the next election.
An election is forced and the existing BDR becomes the DR.
The router with the highest router ID becomes the new BDR.
12
Which two statements describe the use of OSPF DR/BDR elections? (Choose two.)
Elections are always optional.
Elections are required in all WAN networks.
Elections are required in point-to-point networks.
Elections are required in broadcast multiaccess networks.
Elections are sometimes required in NBMA networks.
13

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Refer to the exhibit. As part of an OSPF network, R1 and R2 are trying to become
adjacent neighbors. Although it appears that the two systems are communicating,
neither of the routing tables include OSPF routes received from its neighbor. What
could be responsible for this situation?
R1 and R2 are not on the same subnet.
The Process IDs on each router do not match.
The timer intervals on the routers do not match.
The value set for the Transmit Delay time on both routers is too low.
14

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Refer to the exhibit. What is the purpose of the value 128 shown in bold?
It is the OSPF cost metric.
It is the OSPF administrative distance.
It is the value assigned by the Dijkstra algorithm that designates the distance in hops
to the network.
It is the value assigned to an interface that is used by the DUAL algorithm to
determine the metric.
15

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Refer to the exhibit. What is the purpose of the configuration commands added on
router B?
allows router A to form an adjacency with router B
provides a stable OSPF router ID on router B
provides a method of testing router traffic
creates the OSPF adjacency table on router B
16
Refer to the exhibit. The command ip route 10.16.1.64 255.255.255.252 s0/0/0 is
entered into the router. Why does network 10.16.1.64/30 appear in the routing table in
addition to network 10.16.1.64/27?

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The router views 10.16.1.64/30 and 10.16.1.64/27 as two different networks.
The static route is used as a backup route for packets destined for 10.16.1.64/27.
The AD for static routes is lower than the AD for OSPF routes.
The static route metric is lower than the OSPF metric for the 10.16.1.64/27 network.
17
What is the primary difference between link-state protocols and distance vector
protocols with regard to route calculation?
Distance vector protocols take existing routes from their neighbors and add to them.
Link-state protocols independently calculate full routes.
Link-state protocols calculate and pass full routing tables to all routers in their
associated areas, and distance vector protocols do not.
When determining invalid routes, link-state protocols use split horizon for all route
computations. Distance vector protocols use reverse poisoning.
Distance vector protocols require more CPU and RAM for route calculations than
link-state protocols require.
18
What range of networks are advertised in the OSPF updates by the command
Router1(config-router)# network 192.168.0.0 0.0.15.255 area 0?
192.168.0.0/24 through 192.168.0.15/24
192.168.0.0/24 through 192.168.15.0/24
192.168.15.0/24 through 192.168.31.0/24
192.168.15.0/24 through 192.168.255.0/24
192.168.16.0/24 through 192.168.255.0/24
19

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Refer to the exhibit. When establishing adjacency relationships, which IP address
would router A use to send hello packets to router B?
10.11.0.1
10.11.0.2
10.11.0.255
224.0.0.5
255.255.255.255
20

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Refer to the exhibit. Which router will be elected the DR and which will become the
BDR?
R1 will be DR and R2 will be BDR.

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R1 will be DR and R3 will be BDR.
R2 will be DR and R1 will be BDR.
R2 will be DR and R3 will be BDR.
R3 will be DR and R2 will be BDR.
R3 will be DR and R1 will be BDR.
21
When compared to a distance vector routing protocol, what is a benefit of the
hierarchical design approach that is used in large OSPF networks?
simpler configuration
reduction of router processing requirements
isolation of network instability
less complex network planning
22
What are two advantages of using a link-state routing protocol instead of a distance
vector routing protocol? (Choose two.)
The topology database eliminates the need for a routing table.
Frequent periodic updates are sent to minimize the number of incorrect routes in the
topological database.
Routers have direct knowledge of all links in the network and how they are
connected.
After the initial LSA flooding, routers generally require less bandwidth to
communicate changes in a topology.
A link-state routing protocol requires less router processor power.
23
If a network has converged, what is true about the link-state database held by each
router in the same OSPF area?

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Each router has a link-state database containing the same status information.
Each router has a different link-state database depending on its position within the
network.
The link-state database is stored in a designated router and is accessed by each router
in the area as needed.
The link-state database in each router only contains information about adjacent
routers and the status of their links.
24
Refer to the exhibit. RTRC was recently configured and is not sending the proper
OSPF routes to RTRB, as shown in the RTRB routing table. Based on the RTRC
configuration, what is most likely the problem?
RTRC interfaces are administratively shut down.
The OSPF process ID for RTRC does not match the process ID used on RTRB.

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The interface addresses on RTRC overlap with other addresses in the network.
The OSPF routing configuration on RTRC has a missing or incorrect network
statement.