1.
Refer to the exhibit. All routers are running OSPF. What cost would JAX put in its routing table for the 10.0.0.0/24 network?
Correct Answer
E. 1787
Explanation
In OSPF, the cost metric is calculated based on the bandwidth of the interface. The higher the bandwidth, the lower the cost. Since the question does not provide any specific information about the bandwidth of the interface between JAX and the 10.0.0.0/24 network, we cannot determine the exact cost. However, we can conclude that JAX would put a cost of 1787 in its routing table for the 10.0.0.0/24 network.
2.
Refer to the exhibit. Router1 and Router2 are running OSPF. The show ip ospf neighbor command reveals no neighbors. What is a possible cause?
Correct Answer
D. OSPF hello or dead timers do not match.
Explanation
The possible cause for the show ip ospf neighbor command revealing no neighbors is that the OSPF hello or dead timers do not match. OSPF neighbors establish and maintain adjacency by exchanging hello packets at regular intervals. If the hello or dead timers are not configured to match on Router1 and Router2, they will not be able to establish a neighbor relationship and therefore the show ip ospf neighbor command will not display any neighbors.
3.
A fully converged five router OSPF network has been running successfully for several weeks. All configurations have been saved and no static routes are used. If one router looses power and reboots, what information will be in its routing table after the configuration file is loaded but before OSPF has converged?
Correct Answer
B. Directly connected networks that are operational will be in the routing table.
Explanation
After the router loses power and reboots, the configuration file is loaded but OSPF has not yet converged. This means that the SPF algorithm has not completed all calculations. As a result, no routes will be present in the routing table except for the directly connected networks that are operational. These directly connected networks will be the only ones that the router has immediate knowledge of, while it waits for OSPF to converge and update the routing table with all the routes for the entire network.
4.
Refer to the exhibit. What configuration statements would give the results that are shown in the output of the show ip protocols command?
Correct Answer
C. B(config)# router ospf 1
B(config-router)# router-id 192.168.1.5
Explanation
The configuration statements B(config)# router ospf 1 and B(config-router)# router-id 192.168.1.5 would give the results shown in the output of the show ip protocols command. These statements configure OSPF with process ID 1 and set the router ID to 192.168.1.5. The router ID is used to uniquely identify the router within the OSPF domain.
5.
Correct Answer
A. A FULL adjacency is formed.
6.
What does OSPF use to calculate the cost to a destination network?
Correct Answer
A. Bandwidth
Explanation
OSPF uses bandwidth to calculate the cost to a destination network. The cost is determined based on the bandwidth of the links along the path to the destination. A higher bandwidth link will have a lower cost, indicating a faster and more efficient path. This allows OSPF to select the best path to a destination network based on the available bandwidth.
7.
Refer to the exhibit. The routers in the exhibit are using default OSPF configuration settings to advertise all attached networks. If all of the routers start at the same time, what will be the result of the DR and BDR elections for this single area OSPF network? (Choose three.)
Correct Answer(s)
B. Router A will be DR for 10.4.0.0/16.
C. HQ will be BDR for 10.4.0.0/16.
E. Remote will be DR for 10.5.0.0/16.
Explanation
Router A will be elected as the Designated Router (DR) for the network 10.4.0.0/16. HQ will be elected as the Backup Designated Router (BDR) for the network 10.4.0.0/16. Remote will be elected as the DR for the network 10.5.0.0/16.
8.
What does OSPF use to reduce the number of exchanges of routing information in networks where large numbers of neighbors are present? (Choose two.)
Correct Answer(s)
E. Designated router
F. Backup designated router
Explanation
OSPF (Open Shortest Path First) uses designated routers to reduce the number of exchanges of routing information in networks with a large number of neighbors. The designated router is responsible for collecting and distributing routing information to all other routers within the network. By having a designated router, the other routers only need to exchange routing information with this designated router, rather than exchanging information with every other router in the network. This reduces the amount of routing information exchanges and helps to optimize network performance. The backup designated router is also utilized to provide redundancy in case the designated router fails.
9.
Refer to the exhibit. All routers have been configured with the interface priorities that are shown. All routers were restarted simultaneously. The results of the DR/BDR election are shown. What can be concluded about this network?
Correct Answer
C. The highest router ID was most likely determined via an OSPF router-id statement or statements.
Explanation
The fact that the highest router ID was most likely determined via an OSPF router-id statement or statements can be concluded from the given information. This is because the router with the highest router ID, which is router D, has been elected as the DR. This indicates that the router ID played a significant role in the DR/BDR election process.
10.
Refer to the exhibit. Router A is correctly configured for OSPF. Which OSPF configuration statement or set of statements was entered for router B to generate the exhibited routing table?
Correct Answer
A. B(config-router)# network 192.168.1.0 0.0.0.3 area 0
Explanation
The correct answer is B(config-router)# network 192.168.1.0 0.0.0.3 area 0. This statement is used to enable OSPF on the interface connected to the 192.168.1.0 network with a wildcard mask of 0.0.0.3, which means that only the first two bits of the fourth octet will be considered for OSPF. This will include the IP addresses 192.168.1.0, 192.168.1.1, 192.168.1.2, and 192.168.1.3 in the OSPF routing process.
11.
Refer to the exhibit. Assuming that the routers have default interface OSPF priorities and no configured loopback interfaces, what two roles will router B play on each network segment? (Choose two.)
Correct Answer(s)
A. DR for network 192.168.1.200
E. BDR for network 192.168.1.204
Explanation
Router B will play the role of DR (Designated Router) for network 192.168.1.200 and the role of BDR (Backup Designated Router) for network 192.168.1.204.
12.
Refer to the exhibit. Routers A, B, C, and D are all running OSPF with default router IDs and OSPF interface priorities. Loopback interfaces are not configured and all interfaces are operational. Router D is the DR and router C is the BDR. What happens immediately after the following commands are entered on router A? A(config)# interface fa0/0
A(config-if)# ip ospf priority 255
Correct Answer
D. D will remain the DR. C will remain the BDR.
Explanation
The command "ip ospf priority 255" sets the OSPF priority of the interface fa0/0 on router A to the highest possible value. However, the priority of a router interface only affects the election of the DR and BDR if there is a tie in the OSPF router ID. Since the question states that all routers are running OSPF with default router IDs, the router with the highest router ID will always be elected as the DR, and the router with the second highest router ID will be elected as the BDR. Therefore, even with the highest priority on interface fa0/0, router A will not become the DR or the BDR. Router D will remain the DR and router C will remain the BDR.
13.
What range of networks will be advertised in the OSPF updates by the command Router1(config-router)# network 192.168.0.0 0.0.15.255 area 100?
Correct Answer
B. 192.168.0.0/24 through 192.168.15.0/24
Explanation
The command "network 192.168.0.0 0.0.15.255" in OSPF configuration specifies that the network 192.168.0.0/24 through 192.168.15.0/24 should be advertised in OSPF updates. The wildcard mask 0.0.15.255 indicates that the first 20 bits of the network address should match exactly, while the last 12 bits can be any value. Therefore, the range of networks advertised will include all subnets from 192.168.0.0/24 to 192.168.15.0/24.
14.
Refer to the exhibit. RouterA, RouterB, and RouterC in the diagram are running OSPF on their Ethernet interfaces. Router D was just added to the network. Routers are configured with the loopback interfaces (Lo 0) that are shown in the exhibit. What happens to the OSPF DR/BDR after RouterD is added to the network?
Correct Answer
F. There is no change in the DR or BDR until either current DR or BDR goes down.
Explanation
When RouterD is added to the network, there is no immediate change in the OSPF DR/BDR (Designated Router/Backup Designated Router) election process. The election for DR/BDR only occurs when there is a change in the network or when the current DR/BDR goes down. Therefore, until either the current DR or BDR goes down, there will be no change in the DR or BDR.
15.
Refer to the exhibit. How many OSPF adjacencies must be formed to build the complete topology if a DR or BDR were not elected in this OSPF network?
Correct Answer
C. 6
Explanation
In an OSPF network, each router forms an adjacency with every other router in the network. Without a designated router (DR) or backup designated router (BDR) elected, each router will still form an adjacency with every other router. In the given exhibit, there are a total of 7 routers. To build the complete topology, each router must form an adjacency with the other 6 routers in the network. Therefore, the correct answer is 6.
16.
What is the default administrative distance for OSPF?
Correct Answer
C. 110
Explanation
The default administrative distance for OSPF is 110. Administrative distance is a metric used by routers to determine the best path for forwarding network traffic. OSPF is a routing protocol that uses this metric to determine the best path within an autonomous system (AS). A lower administrative distance indicates a more preferred route. In the case of OSPF, a default administrative distance of 110 means that OSPF routes are preferred over routes from other routing protocols with higher administrative distances.
17.
Refer to the exhibit. Which command sequence on RouterB will redistribute a gateway of last resort to the other routers in OSPF area 0?
Correct Answer
B. RouterB(config)# ip route 0.0.0.0 0.0.0.0 172.16.6.6
RouterB(config)# router ospf 10
RouterB(config-router)# default-information originate
Explanation
The correct answer is RouterB(config)# ip route 0.0.0.0 0.0.0.0 172.16.6.6 and RouterB(config)# router ospf 10 RouterB(config-router)# default-information originate. This command sequence configures RouterB to redistribute the default route (gateway of last resort) into OSPF area 0. The first command sets up the default route with the next hop IP address of 172.16.6.6. The second command enables RouterB to advertise this default route to other routers in OSPF area 0. By redistributing the default route, other routers in the OSPF network will be aware of the gateway of last resort and can use it to reach destinations outside of the OSPF domain.
18.
Which two statements describe the use of OSPF DR/BDR elections? (Choose two.)
Correct Answer(s)
D. Elections are required in broadcast multiaccess networks.
E. Elections are sometimes required in NBMA networks.
Explanation
OSPF DR/BDR elections are used in broadcast multiaccess networks to select a designated router (DR) and a backup designated router (BDR) to reduce the amount of OSPF traffic and simplify the network. In these networks, all routers are connected to a common network segment, and the DR and BDR are responsible for exchanging OSPF information with other routers on behalf of the entire network. This ensures that only the DR and BDR need to maintain a full OSPF database, reducing the amount of OSPF traffic and processing power required by other routers. In NBMA networks, such as Frame Relay or X.25, elections are sometimes required if the network does not support multicast communication, and a designated router is needed to represent the network.
19.
Refer to the exhibit. What does the “2″ stand for in the router ospf 2 statement?
Correct Answer
C. The number 2 indicates the number of networks advertised by OSPF.
Explanation
The number 2 indicates the number of networks advertised by OSPF.
20.
Refer to the exhibit. The network administrator wants to set the router ID of Router1 to 192.168.100.1. What steps can the administrator take to accomplish this?
Correct Answer
D. Nothing, the router-id of Router1 is already 192.168.100.1
21.
Refer to the exhibit. What must be received between neighbors to prevent the dead time that is shown in the exhibit from reaching zero?
Correct Answer
C. Hello packets
Explanation
To prevent the dead time from reaching zero, hello packets must be received between neighbors. Hello packets are used by routing protocols to establish and maintain neighbor relationships. By exchanging hello packets, routers can periodically check the status and availability of their neighboring routers. This helps to ensure that the routers are still connected and functioning properly. If hello packets are not received within a certain time frame, the dead time will reach zero, indicating that the neighbor is no longer reachable.
22.
Refer to the exhibit. What does the “O*E2″ from the “O*E2 0.0.0.0/0 [110/1] via 192.168.1.1, 00:05:34, Serial0/0″ line represent?
Correct Answer
D. An external OSPF route that will not increment in cost.
Explanation
The "O*E2" in the "O*E2 0.0.0.0/0 [110/1] via 192.168.1.1, 00:05:34, Serial0/0" line represents an external OSPF route that will not increment in cost.
23.
Refer to the exhibit. Which network command or set of commands will cause OSPF to be enabled for any R1 interface connected to the exhibited subnets?
Correct Answer
B. R1(config-router)# network 10.1.0.0 0.0.0.255 area 0
R1(config-router)# network 10.1.1.0 0.0.0.255 area 0
R1(config-router)# network 10.1.2.4 0.0.0.3 area 0
Explanation
The correct answer is a combination of three network commands. The first command "network 10.1.0.0 0.0.0.255 area 0" enables OSPF for any interface on R1 that falls within the range of 10.1.0.0 to 10.1.0.255. The second command "network 10.1.1.0 0.0.0.255 area 0" enables OSPF for any interface on R1 that falls within the range of 10.1.1.0 to 10.1.1.255. The third command "network 10.1.2.4 0.0.0.3 area 0" enables OSPF for any interface on R1 that falls within the range of 10.1.2.4 to 10.1.2.7. Together, these commands ensure that OSPF is enabled for all interfaces connected to the exhibited subnets.
24.
Refer to the exhibit. What is the cost of the route to the 10.0.0.0 network?
Correct Answer
C. 1786
Explanation
The cost of the route to the 10.0.0.0 network is 1786.
25.
What three parameters must be indentical between OSPF routers in order to form an adjacency? (Choose three.)
Correct Answer(s)
A. Area id
D. Hello interval
E. Network type
Explanation
In order for OSPF routers to form an adjacency, three parameters must be identical: area id, hello interval, and network type. The area id is used to group routers into OSPF areas, and routers must be in the same area to form an adjacency. The hello interval is the time interval at which OSPF routers send hello packets to discover and maintain neighbor relationships. The network type defines how OSPF operates on a particular network interface. These three parameters must match between routers to establish OSPF adjacency.