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This preview shows page 203 - 206 out of 296 pages. 172.16.20.2 172.16.26.254 172.16.47.254 172.16.48.5 112. What are two reasons that will prevent two routers from forming an OSPFv2 adjacency? (Choose two.) mismatched subnet masks on the link interfaces a mismatched Cisco IOS version that is used use of private IP addresses on the link interfaces one router connecting to a FastEthernet port on the switch and the other connecting to a GigabitEthernet port mismatched OSPF Hello or Dead timers 113. Which three addresses could be used as the destination address for OSPFv3 messages? (Choose three.) FF02::5 FF02::6 FF02::A 2001:db8:cafe::1 FF02::1:2 FE80::1 114. Refer to the exhibit. What is the OSPF cost to reach the West LAN 172.16.2.0/24 from East? 65* 115. The network address 172.18.9.128 with netmask 255.255.255.128 is matched by which wildcard mask? 0.0.0.31 0.0.0.255 0.0.0.127* 0.0.0.63 116. As part of the new security policy, all switches on the network are configured to automatically learn MAC addresses for each port. All running configurations are saved at the start and close of every business day. A severe thunderstorm causes an extended power outage several hours after the close of business. When the switches are brought back online, the dynamically learned MAC addresses are retained. Which port security configuration enabled this? auto secure MAC addresses dynamic secure MAC addresses static secure MAC addresses sticky secure MAC addresses 117. Refer to the exhibit. A small business uses VLANs 2, 3, 4, and 5 between two switches that have a trunk link between them. What native VLAN should be used on the trunk if Cisco best practices are being implemented? 1 2 3 4 5 6 11 118. A router learns of multiple routes toward the same destination. Which value in a routing table represents the trustworthiness of learned routes and is used by the router to determine which route to install into the routing table for this specific situation? routing protocol outgoing interface metric administrative distance How often do switches send Bridge Protocol Data Units (BPDUs)? Every 2 sec Name the STP port states in order Blocking, Listening, Learning, Forwarding and Disabled What's the default Cisco Bridge ID? 32768 Which command will show you the Root Bridge and priority for a VLAN? show spanning-tree vlan x What's the STP port cost for a 100 Mbps link? 19 When a port that's configured with the _ _ feature receives a BPDU, it immediately transitions to the errdisable state BPDU Guard The _ _ feature effectively disables STP on the selected ports by preventing them from sending or receiving any BPDUs BPDU Filter Which 2 commands will force the switch to become the Root Bridge for a VLAN? spanning-tree vlan x priority x spanning-tree vlan x root [primary|secondary] Contrary to popular belief, the Port Fast feature does not disable Spanning Tree on the selected port as the port can still send and receive BPDUs. T/F? Upload your study docs or become a Course Hero member to access this document Upload your study docs or become a Course Hero member to access this document End of preview. Want to read all 296 pages? Upload your study docs or become a Course Hero member to access this document CCNA 3 v7 Modules 1 – 2: OSPF Concepts and Configuration Exam Answers1. What is a function of OSPF hello packets?to send specifically requested link-state records 2. Which OPSF packet contains the different types of link-state advertisements?hello 3. Which three statements describe features of the OSPF topology table? (Choose three.)It is a link-state database that represents the network topology.* 4. What does an OSPF area contain?routers that share the same router ID 5. What is used to facilitate hierarchical routing in OSPF?the use of multiple áreas* Explanation: OSPF supports the concept of areas to prevent larger routing tables, excessive SPF calculations, and large LSDBs. Only routers within an area share link-state information. This allows OSPF to scale in a hierarchical fashion with all areas that connect to a backbone area. 6. Which OSPF data structure is identical on all OSPF routers that share the same area?forwarding database Explanation: Regardless of which OSPF area a router resides in, the adjacency database, routing table, and forwarding database are unique for each router. The link-state database lists information about all other routers within an area and is identical across all OSPF routers participating in that area. 7. Which step does an OSPF-enabled router take immediately after establishing an adjacency with another router?builds the topology table Explanation: The OSPF operation steps are as follows: 8. A network engineer has manually configured the hello interval to 15 seconds on an interface of a router that is running OSPFv2. By default, how will the dead interval on the interface be affected?The dead interval will not change from the default value. Explanation: Cisco IOS automatically modifies the dead interval to four times the hello interval. 9. Refer to the exhibit. CCNA 3 v7.0 Modules 1 – 2 Exam Answers p9 A network administrator has configured the OSPF timers to the values that are shown in the graphic. What is the result of having those manually configured timers?R1 automatically adjusts its own timers to match the R2 timers. Explanation: The dead timer (20 seconds) on R1 expires before the next hello packet from R2 (25 seconds). 10. To establish a neighbor adjacency two OSPF routers will exchange hello packets. Which two values in the hello packets must match on both routers? (Choose two.)dead interval* Explanation: The hello and dead interval timers contained in a hello packet must be the same on neighboring routers in order to form an adjacency. 11. What is the default router priority value for all Cisco OSPF routers?0 Explanation: The router priority value is used in a DR/BDR election. The default priority for all OSPF routers is 1 but it can be manually altered to any value 0 to 255. 12. Which type of OSPFv2 packet contains an abbreviated list of the LSDB of a sending router and is used by receiving routers to check against the local LSDB?database description* Explanation: The database description (DBD) packet contains an abbreviated list of the LSDB sent by a neighboring router and is used by receiving routers to check against the local LSDB. 13. In an OSPF network when are DR and BDR elections required?when the two adjacent neighbors are interconnected
over a point-to-point link Explanation: When the routers are interconnected over a common Ethernet network, then a designated router (DR) and a backup DR (BDR) must be elected. 14. When an OSPF network is converged and no network topology change has been detected by a router, how often will LSU packets be sent to neighboring routers?every 5 minutes Explanation: After all LSRs have been satisfied for a given router, the adjacent routers are considered synchronized and in a full state. Updates (LSUs) are sent to neighbors only under the following conditions: 15. What will an OSPF router prefer to use first as a router ID?a loopback interface that is configured with the highest IP address on the router Explanation: The first preference for an OSPF router ID is an explicitly configured 32-bit address. This address is not included in the routing table and is not defined by the network command. If a router ID that is configured through the router-id command is not available, OSPF routers next use the highest IP address available on a loopback interface, as loopbacks used as router IDs are also not routable addresses. Lacking either of these alternatives, an OSPF router will use the highest IP address from its active physical interfaces. 16. What are the two purposes of an OSPF router ID? (Choose two.)to uniquely identify the router within the OSPF domain* Explanation: OSPF router ID does not contribute to SPF algorithm calculations, nor does it facilitate the transition of the OSPF neighbor state to Full. Although the router ID is contained within OSPF messages when router adjacencies are being established, it has no bearing on the actual convergence process. 17. Refer to the exhibit.CCNA 3 v7.0 Modules 1 – 2 Exam Answers p17 If no router ID was manually configured, what would router Branch2 use as its OSPF router ID?10.0.0.1 Explanation: In OSPFv2, a Cisco router uses a three-tier method to derive its router ID. The first choice is the manually configured router ID with the router-id command. If the router ID is not manually configured, the router will choose the highest IPv4 address of the configured loopback interfaces. Finally if no loopback interfaces are configured, the router chooses the highest active IPv4 address of its physical interfaces. 18. A network technician issues the following commands when configuring a router:R1(config)# router ospf 11 What does the number 11 represent?the OSPF process ID on R1* Explanation: There is no autonomous system number to configure on OSPF. The area number is located at the end of the network statement. The cost of a link can be modified in the interface configuration mode. The process ID is local to the router. 19. An OSPF router has three directly connected networks; 172.16.0.0/16, 172.16.1.0/16, and 172.16.2.0/16. Which OSPF network command would advertise only the 172.16.1.0 network to neighbors?router(config-router)# network 172.16.1.0 0.0.255.255 area 0* Explanation: To advertise only the 172.16.1.0/16 network the wildcard mask used in the network command must match the first 16-bits exactly. To match bits exactly, a wildcard mask uses a binary zero. This means that the first 16-bits of the wildcard mask must be zero. The low order 16-bits can all be set to 1. 20. Refer to the exhibit.CCNA 3 v7.0 Modules 1 – 2 Exam Answers p20 Which three statements describe the results of the OSPF election process of the topology that is shown in the exhibit? (Choose three.)R3 will be elected BDR.* Explanation: R2 will be elected DR because it has the highest priority of 255, all of the others have a priority of 1. R3 will be elected BDR because it has the numerically highest router-ID of 192.168.1.4. The R4 router-ID is 172.16.1.1 because it is the IPv4 address attached to the loopback 0 interface. 21. Refer to the exhibit.CCNA 3 v7.0 Modules 1 – 2 Exam Answers p21 If the switch reboots and all routers have to re-establish OSPF adjacencies, which routers will become the new DR and BDR?Router R4 will become the DR and router R1 will become the
BDR.* Explanation: OSPF elections of a DR are based on the following in order of precedence: 22. By default, what is the OSPF cost for any link with a bandwidth of 100 Mb/s or greater?100000000 Explanation: OSPF uses the formula: Cost = 100,000,000 / bandwidth. Because OSPF will only use integers as cost, any bandwidth of 100 Mb/s or greater will all equal a cost of 1. 23. Refer to the exhibit.CCNA 3 v7.0 Modules 1 – 2 Exam Answers p23 What is the OSPF cost to reach the router A LAN 172.16.1.0/24 from B?782 Explanation: The formula used to calculate the OSPF cost is as follows: 24. Refer to the exhibit.CCNA 3 v7.0 Modules 1 – 2 Exam Answers p24 On which router or routers would a default route be statically configured in a corporate environment that uses single area OSPF as the routing protocol?R0-A* Explanation: The default route is applied to the router that connects to the Internet, or R0-A. R0-A then distributes that default route using the OSPF routing protocol. 25. What command would be used to determine if a routing protocol-initiated relationship had been made with an adjacent router?ping Explanation: While the show ip interface brief and ping commands can be used to determine if Layer 1, 2, and 3 connectivity exists, neither command can be used to determine if a particular OSPF or EIGRP-initiated relationship has been made. The show ip protocols command is useful in determining the routing parameters such as timers, router ID, and metric information associated with a specific routing protocol. The show ip ospf neighbor command shows if two adjacent routers have exchanged OSPF messages in order to form a neighbor relationship. 26. Refer to the exhibit.CCNA 3 v7.0 Modules 1 – 2 Exam Answers p26 Which command did an administrator issue to produce this output?R1#
show ip ospf interface serial0/0/1* 27. Which command is used to verify that OSPF is enabled and also provides a list of the networks that are being advertised by the network?show ip interface brief Explanation: The command show ip ospf interface verifies the active OSPF interfaces. The command show ip interface brief is used to check that the interfaces are operational. The command show ip route ospf displays the entries that are learned via OSPF in the routing table. The command show ip protocols checks that OSPF is enabled and lists the networks that are advertised. 28. Refer to the exhibit.CCNA 3 v7.0 Modules 1 – 2 Exam Answers p28 A network administrator has configured OSPFv2 on the two Cisco routers but PC1 is unable to connect to PC2. What is the most likely problem?Interface Fa0/0 has not been activated for OSPFv2 on router R2.* Explanation: If a LAN network is not advertised using OSPFv2, a remote network will not be reachable. The output displays a successful neighbor adjacency between router R1 and R2 on the interface S0/0 of both routers. 29. What is the recommended Cisco best practice for configuring an OSPF-enabled router so that each router can be easily identified when troubleshooting routing issues?Configure a value using the router-id command.* Explanation: A Cisco router is assigned a router ID to uniquely identify it. It can be automatically assigned and take the value of the highest configured IP address on any interface, the value of a specifically-configured loopback address, or the value assigned (which is in the exact form of an IP address) using the router-id command. Cisco recommends using the router-id command. 30. Which step in the link-state routing process is described by a router running an algorithm to determine the best path to each destination?load balancing equal-cost paths 31. An administrator is configuring single-area OSPF on a router. One of the networks that must be advertised is 192.168.223.0 255.255.254.0. What wildcard mask would the administrator use in the OSPF network statement?0.0.1.255* 32. What is the format of the router ID on an OSPF-enabled router?a unique router host name that is configured on the router Explanation: A router ID is a 32-bit number formatted like an IPv4 address and assigned in order to uniquely identify a router among OSPF peers. 33. Question as presented:DUAL is the algorithm used by EIGRP. In multiarea OSPF, OSPF is implemented using multiple areas, and all of them must be connected to the backbone area. 34. After modifying the router ID on an OSPF router, what is the preferred method to make the new router ID effective?HQ# copy running-config startup-config Explanation: To modify a router-id on an OSPF-enabled router, it is necessary to reset the OSPF routing process by entering either the clear ip ospf process command or the reload command. 35. In an OSPFv2 configuration, what is the effect of entering the command network 192.168.1.1 0.0.0.0 area 0?It allows all 192.168.1.0 networks to be advertised. Explanation: Entering the command network 192.168.1.1 0.0.0.0 area 0 will turn on only the interface with that IP address for OSPF routing. It does not change the router ID. Instead, OSPF will use the network that is configured on that interface. 36. What is the reason for a network engineer to alter the default reference bandwidth parameter when configuring OSPF?to force that specific link to be used in the destination route Explanation: By default, Fast Ethernet, Gigabit, and 10 Gigabit Ethernet interfaces all have a cost of 1. Altering the default reference bandwidth alters the cost calculation, allowing each speed to be more accurately reflected in the cost. 37. Open the PT Activity. Perform the tasks in the activity instructions and then answer the question.Which task has to be performed on Router 1 for it to establish an OSPF adjacency with Router 2?Issue the clear ip ospf process command. Explanation: Each interface on the link connecting the OSPF routers must be in the same subnet for an adjacency to be established. The IP address subnet mask on FastEthernet interface 0/0 must be changed to 255.255.255.0. The FastEthernet interface 0/0 is not passive. The 10.0.1.0/24 network is only connected to Router2 so should not be advertised by Router1. The clear ip ospf process command will start the OPSF process on Router1 but will not cause an adjacency to be established if the subnet mask mismatch on the connecting interfaces still exists. 38. Match the description to the term. (Not all options are used.)CCNA 3 v7.0 Modules 1 – 2 Exam Answers p38 39. What is a benefit of multiarea OSPF routing?Topology changes
in one area do not cause SPF recalculations in other areas.* Explanation: With multiarea OSPF, only routers within an area share the same link-state database. Changes to the network topology in one area do not impact other areas, which reduces the number of SPF algorithm calculations and the of link-state databases. 40. Match the OSPF state with the order in which it occurs. (Not all options are used.)CCNA 3 v7.0 Modules 1 – 2 Exam Answers p40 41. What indicates to a link-state router that a neighbor is unreachable?if
the router no longer receives hello packets* Explanation: OSPF routers send hello packets to monitor the state of a neighbor. When a router stops receiving hello packets from a neighbor, that neighbor is considered unreachable and the adjacency is broken. 42. Which three OSPF states are involved when two routers are forming an adjacency? (Choose three.)Exchange Explanation: OSPF operation progresses through 7 states for establishing neighboring router adjacency, exchanging routing information, calculating the best routes, and reaching convergence. The Down, Init, and Two-way states are involved in the phase of neighboring router adjacency establishment. 43. Refer to the exhibit.CCNA 3 v7.0 Modules 1 – 2 Exam Answers p43 Suppose that routers B, C, and D have a default priority, and router A has a priority 0. Which conclusion can be drawn from the DR/BDR election process?If the priority of router C is changed to 255, then it will become the DR. Explanation: If the priority is set to 0, the router is not capable of becoming the DR, so router A cannot be the DR. OSPF DR and BDR elections are not preemptive. If a new router with a higher priority or higher router ID is added to the network after the DR and BDR election, the newly added router does not take over the DR or the BDR role. 44. An administrator is configuring single-area OSPF on a router. One of the networks that must be advertised is 64.102.0.0 255.255.255.128. What wildcard mask would the administrator use in the OSPF network statement?0.0.31.255 45. Which command will a network engineer issue to verify the configured hello and dead timer intervals on a point-to-point WAN link between two routers that are running OSPFv2?show ipv6 ospf interface serial 0/0/0 Explanation: The show ip ospf interface serial 0/0/0 command will display the configured hello and dead timer intervals on a point-to-point serial WAN link between two OSPFv2 routers. The show ipv6 ospf interface serial 0/0/0 command will display the configured hello and dead timer intervals on a point-to-point serial link between two OSPFv3 routers. The show ip ospf interface fastethernet 0/1 command will display the configured hello and dead timer intervals on a multiaccess link between two (or more) OSPFv2 routers. The show ip ospf neighbor command will display the dead interval elapsed time since the last hello message was received, but does not show the configured value of the timer. 46. An administrator is configuring single-area OSPF on a router. One of the networks that must be advertised is 128.107.0.0 255.255.255.192. What wildcard mask would the administrator use in the OSPF network statement?0.0.63.255 47. Match each OSPF packet type to how it is used by a router. (Not all options are used.)CCNA 3 v7.0 Modules 1 – 2 Exam Answers p47 48. Which step in the link-state routing process is described by a router building a link-state database based on received LSAs?building the topology table* 49. Which three OSPF states are involved when two routers are forming an adjacency? (Choose three.)Init* 50. An administrator is configuring single-area OSPF on a router. One of the networks that must be advertised is 198.19.0.0 255.255.252.0. What wildcard mask would the administrator use in the OSPF network statement?0.0.63.255 51. An administrator is configuring single-area OSPF on a router. One of the networks that must be advertised is 128.107.0.0 255.255.252.0. What wildcard mask would the administrator use in the OSPF network statement?0.0.3.255* Which two reasons will prevent two routers from forming an OSPFv3 adjacency?What are two reasons that will prevent two routers from forming an OSPFv2 adjacency? (. a mismatched Cisco IOS version that is used.. mismatched OSPF Hello or Dead timers.. mismatched subnet masks on the link interfaces.. use of private IP addresses on the link interfaces.. Which command will verify that a router that is running OSPFv2 has formed an adjacency?The show ip ospf neighbor command is used to verify that the router has formed an adjacency with its neighboring routers.
What are two reasons for creating an OSPF network with multiple areas?The reason you would create multiple area types is to avoid overwhelming routers with a huge routing table and topology database when they do not need to understand this information. To reduce router overhead in a large OSPF network, you can create different types of areas.
What is the order of preference for choosing the router ID of an OSPF router?OSPF uses the following criteria to select the router ID: Manual configuration of the router ID. Highest IP address on a loopback interface. Highest IP address on a non-loopback interface.
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What are two reasons that will prevent two routers from forming an OSPFv2 adjacency? (Choose two)
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