ActualTests.Cisco.640-802.Exam.Q.and.A.08.15.08-DDU (1130589), страница 55
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It allows extensive control of routing updatesF. None of the aboveAnswer: A, C, EExplanation:The following describes some of the features and functionality of the OSPF protocol:Open Shortest Path First* Each router discovers its neighbors on each interface. The list of neighbors is kept in aneighbor table.* Each router uses a reliable protocol to exchange topology information with itsneighbors.* Each router places the learned topology information into its topology database.* Each router runs the SPF algorithm against its own topology database.* Each router runs the SPF algorithm against its own topology database to calculate thebest routes to each subnet in the database.* Each router places the best roué to each subnet into the IP routing table.The following list points out some of the key features of OSPF:* Converges very quickly - from the point of recognizing a failure, it often can convergein less than 10 seconds.* Supports VLSM.* Uses short Hello messages on a short regular interval, with the absence of hellomessages indicating that a neighbor is no longer reachable.* Sends partial updates when link status changes and floods full updates every 30minutes.
The flooding, however, does not happened all at once, so the overhead sminimal.* Uses cost for the metric.Incorrect Answers:B. This is incorrect because the hierarchical design characteristics of OSPF actuallyreduce the overhead on larger networks.D. This is not true as OSPF doesn't route between Autonomous Systems. OSPF is anIGP. Routing between autonomous systems is reserved for EGP protocols such as BGP.QUESTION 491:Which of the following are true statements regarding the characteristics of OSPFareas? (Select all that apply)A. All OSPF networks require the use of multiple areasB.
Multiple OSPF areas must connect to area 0C. Single area OSPF networks must be configured in area 1Actualtests.com - The Power of Knowing640-802D. Areas can be assigned any number from 0 to 63535E. Area 0 is called the backbone areaF. Each OSPF area need to be configured with a loopback interfaceAnswer: B, EExplanation:OSPF divides its routing domain into areas.
Area 0, the backbone, is required. Thisdivides interior routing into two levels. If traffic must travel between two areas, thepackets are first routed to the backbone. This may cause non-optimal routes, sinceinterarea routing is not done until the packet reaches the backbone. Once there, it isrouted to the destination area, which is then responsible for final delivery. This layeringpermits addresses to be consolidated by area, reducing the size of the link state databases.All areas must be connected to area 0, either directly or through the use of virtual links.Incorrect Answers:A. OSPF network can only consist of a single area.C.
Single area networks can use any area number. If more than one area is configured inthe network, then at least one of the areas must be area 0.D. The area-id can be an integer between 0 and 4294967295.F. While loopback interfaces are commonly used in OSPF networks, it is not arequirement.QUESTION 492:On what kinds of networks does the OSPF protocol elect a backup designatedrouter? (Select all that apply)A. Point-to-pointB.
Point to multipointC. BroadcastD. Non-broadcast multi-accessE. None of the aboveAnswer: C, DExplanation:The DR and BDR election process is performed on broadcast and non-broadcastmulti-access networks.Incorrect Answers:A, B: There is no DR or BDR on point to point and point to multipoint links. On a pointto point link, only two routers exist so there is no need for a DR or BDR.QUESTION 493:Actualtests.com - The Power of Knowing640-802Three Certkiller routers are configured for OSPF area 0 as shown in the diagrambelow:You wish to ensure that router CK2 will be preferred as the designated router (DR)for the 172.16.1.0 /24 LAN segment.What configuration tasks could be used to establish this preference? (Choose allthat apply)A.
Configure the priority value of the Fa0/0 interface of Router CK2 to a higher valuethan any other interface on the Ethernet network.B. Change the router id for Router CK2 by assigning the IP address 172.16.1.130/24 tothe Fa0/0 interface of Router CK2 .C. Configure a loopback interface on Router CK2 with an IP address higher than any IPaddress on the other routers.D. Change the priority value of the Fa0/0 interface of Router CK2 to zero.E.Change the priority values of the Fa0/0 interfaces of Router CK1 and Router CK3 to zero.F. No further configuration is necessary.G. All of the above will make CK2 the DRAnswer: A, C, EExplanation:In order to ensure that a router will become the OSPF DR for any given segment, thereare a number of options.
One way is to manually configure the interface priority asdescribed in option A above using the "ip ospf priority" interface configurationcommand. The second method is described in option C. OSPF routers will always use theloopback interface IP address as the router ID, when configured, and the router with thehighest IP address will be chosen as the DR when the priorities are the same.
The finalActualtests.com - The Power of Knowing640-802method is to change the priority of the other routers in the segment to zero. When theOSPF priority is set to 0, the router is ineligible to become the DR or the BDR. ImportantNote: The OSPF DR/BDR election process is not pre-emptive, so any changes to thenetwork regarding the DR/BDR election process will only occur when the routers arerestarted.Incorrect Answers:B.
This method will not work as the router ID is taken by using the highest IP address ofall interfaces in the router, or from the loopback interface if it is configured. Althoughchoosing this option will give router CK2 the highest IP address on the LAN segment, therouter ID will be taken from the highest IP address in the router, which as shown will be192.168.0.101.D.
This will make CK2 ineligible to become either the DR or the BDR.QUESTION 494:Certkiller uses OSPF in their WAN. The OSPF Hello protocol performs which of thefollowing tasks in this network? (Choose two)A. It maintains neighbor relationships.B. It broadcasts hello packets throughout the internetwork to discover all routers that arerunning OSPF.C. It uses timers to elect the router with the fastest links as the designated router.D. It negotiates correctness parameters between neighboring interfaces.E.
It detects unreachable neighbors in 90 second intervals.F. It provides dynamic neighbor discovery.G. It is only used once when the router boots upAnswer: A, FQUESTION 495:CK1 and CK2 are OSPF routers on a point-point link. On this point-to-pointnetwork, OSPF hello packets are addressed to which address?A.
192.168.0.5B. 254.255.255.255C. 223.0.0.1D. 172.16.0.1E. 224.0.0.5F. 127.0.0.1G. None of the aboveAnswer: EActualtests.com - The Power of Knowing640-802Explanation:The multicast IP address 224.0.0.5 is known as 'AllSPFRouters.' All routers runningOSPF should be prepared to receive packets sent to this address since hello packets arealways sent to this destination. Also, certain OSPF protocol packets are sent to thisaddress during the flooding procedure.Incorrect Answers:A. This is the IP address reserved for the internal loopback on PC hosts. All windowsbased PC's will use this internal IP address, assuming that the TCP/IP stack is correctlyinstalled.B, D.
These addresses are part of the range of addresses reserved for internal use, asdefined in RFC 1918.QUESTION 496:Which of the following statements below best describe the process identifier that isused to run OSPF on a Certkiller router? (Choose two)A. It is an optional parameter required only if multiple OSPF processes are running onthe router.B. It is locally significant.C. It is needed to identify a unique instance of an OSPF database.D. All routers in the same OSPF area must have the same process ID if they are toexchange routing information.E. It is globally significant.F.
It is shared among all OSPF routersAnswer: B, CExplanation:The OSPF process ID is locally significant, and is only used by the local router todiscriminate between multiple OSPF processes. In any given OSPF network, the processID's do not need to match between neighboring routers. This is in contrast to otherrouting protocols, such as EIGRP.Additional info:router ospf process-idno router ospf process-idprocess-idInternally used identification parameter for an OSPF routing process. It is locallyassigned and can be any positive integer. A unique value is assigned for each OSPFrouting process.Reference:http://www.cisco.com/en/US/products/sw/iosswrel/ps1826/products_command_summary_chapter09186a00800dActualtests.com - The Power of Knowing640-802QUESTION 497:The interface information for router Certkiller 3 is displayed below:Router Certkiller 3 was just successfully rebooted.
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