ActualTests.Cisco.640-802.Exam.Q.and.A.08.15.08-DDU (1130589), страница 53
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Only routers can split boundaries (horizons) between concentric networks.B. Each AS must keep routing tables converged to prevent dead routes from beingadvertised across boundaries.C. Networks can only remain fully converged if all information is sent out all activeinterfaces.D. Information about a route should not be sent back in the direction from which theoriginal update came.E. Distance vector protocols need fall back routers that are responsible for momentaryloops.Answer: DExplanation:Simply said, the rule of split horizons says that routing information should not be sent outthe same interface that it was learned on. This is used to prevent routing loops in thenetwork, but it can also cause problems on NBMA networks, such as a hub and spokeframe relay network.
Split horizons include two related concepts that affect what routesare included in a routing update:An update does not include the subnet of the interface out which the update is sentAll routes with outgoing interface of interface x are not included in updates sent out thatsame interface x.Incorrect AnswersA. There is no such requirementC. This is not a feature of split horizonB.
This is not a related feature for split horizonE. Distance vector protocols updates routing table at regular intervals instead ofTopology changesReference: Wendell Odom. CISCO CCNA Certification Guide (2000 Cisco Press) Page369.QUESTION 476:Which of the following statements are correct in regard to classless routingprotocols? (Select two)A.
Discontiguous subnets are not allowed.B. Variable length subnet masks are allowed.Actualtests.com - The Power of Knowing640-802C. RIP v1 is a classless routing protocol.D. IGRP supports classless routing within the same autonomous system.E. RIP v2 supports classless routing.Answer: B, EExplanation:Classless and Classful Routing ProtocolsSome routing protocols must consider the Class A, B, or C network number that a subnetresides in when performing some of its tasks.
Other routing protocols can ignore Class A,B, and C rules altogether. Routing protocols that must consider class rules are calledclassful routing protocols; those that do not need to consider class rules are calledclassless routing protocols.You can easily remember which routing protocols fall into each category because of onefact:Classful routing protocols do not transmit the mask information along with the subnetnumber, whereas classless routing protocols do transmit mask information.You might recall that routing protocols that support VLSM do so because they send maskinformation along with the routing information.
Table 7-3 lists the routing protocols andwhether they transmit mast information, support VLSM, and are classless or classful.Table 7-3 Interior IP Routing Protocol: Classless or Classful?Reference: CCNA ICND Exam Certification Guide by Wendell Odem, Pg.233QUESTION 477:The Certkiller WAN is displayed below:Actualtests.com - The Power of Knowing640-802Assume that the routing Protocol referenced in each choice below is configurationwith its default settings and the given routing protocol is running on all the routers.Which two conditional statements accurately state the path that will be chosenbetween network 10.1.0.0 and 10.3.2.0 for the routing protocol mentioned? (ChooseTwo)A.
If RIPv2 is the routing protocol; the path will be from Certkiller 1 to Certkiller 3 toCertkiller 4 to Certkiller 5.B. If RIPv2 is the routing protocol; the path will be from Certkiller 1 to Certkiller 5.C. If EIGRP is the routing protocol; the path will be from Certkiller 1 to Certkiller 3to Certkiller 4 to Certkiller 5.D. If EIGRP is the routing protocol, the path will be from Certkiller 1 to Certkiller 2to Certkiller 5.E.
If OSPF is the routing protocol; the path will be from Certkiller 1 to Certkiller 5.Answer: B, CExplanation:RIP, IGRP both are called the distance vector Protocols. RIP uses the number of hops asa metric.RIP:_ Based on distance vector Logic_ Uses hop count for the metric_ Sends periodic full routing updates every 30 seconds_ Converges slowly, often taking 3 to 5 minutes_ Does not support VLSM, also making it a classful routing protocol (RIP V)EIGRPEIGRP calculates the metric based on a mathematical formula that you do not really needto know for the exam. The formula uses bandwidth and delay as input and results in aninteger value, the metric, between 1 and 4,294,967,295.When RIP is used as the Routing Protocol, it selects CK1 - CK5 because it has less hops.When EIGRP is used as the Routing Protocol, it selects CK1 - CK3 - CK4 - CK5 because thatpath contains more bandwidth.
By default, EIGRP uses bandwidth and delay to calculatethe path.QUESTION 478:A large corporation that frequently integrates networks from newly acquiredbusinesses has just decided to use OSPF as the corporate routing protocol instead ofEIGRP. What two benefits will the change from EIGRP to OSPF provide to thecorporation? (Choose two)A.
The ability to automatically summarize networksB. The ability to redistribute default and static routesC. The ability to use VLSMActualtests.com - The Power of Knowing640-802D. The ability to support multi-vendor routersE. The ability to create a hierarchical design using areasAnswer: D, EExplanation:Open Shortest Path First (OSPF) is a routing protocol developed for Internet Protocol(IP) networks by the Interior Gateway Protocol (IGP) working group of the InternetEngineering Task Force (IETF). Unlike, EIGRP, OSPF is standards based which issupported by multiple router vendors.Unlike RIP and EIGRP, OSPF can operate within a hierarchy.
The largest entity withinthe hierarchy is the autonomous system (AS), which is a collection of networks under acommon administration that share a common routing strategy. OSPF is an intra-AS(interior gateway) routing protocol, although it is capable of receiving routes from andsending routes to other AS's.An AS can be divided into a number of areas, which are groups of contiguous networksand attached hosts. Routers with multiple interfaces can participate in multiple areas.These routers, which are called Area Border Routers, maintain separate topologicaldatabases for each area.QUESTION 479:Please study the exhibit shown below carefully:Actualtests.com - The Power of Knowing640-802Given the partial output from the show running-config command displayed on bothCertkiller routers, which routing protocol would be used to route packets to the172.16.5.48/28 network from RouterB?A. OSPFB.
RIPC. EIGRPD. No route will be installed to 172.16.5.48/28.E. Unable to determine based on the information providedAnswer: AExplanation:Normally, routers will choose EIGRP routes over OSPF and RIP routes because EIGRPhas a lower administrative distance than the other two. However, in this case, autosummarization has been turned on, so the routers will automatically summarize at thenetwork boundary. This will result in each router sending out only the summarized,172.16.0.0/16 route.However, OSPF does not summarize by default so RouterB will receive the specific172.16.5.48/28 announcement from RouterA via OSPF. Because routers always chooseActualtests.com - The Power of Knowing640-802the most specific route to the destination, regardless of the administrative distance,RouterB will use this OSPF route.QUESTION 480:Which characteristics are representative of link-state routing protocols? (Choosethree)A.
Provides common view of entire topologyB. Utilizes event-triggered updatesC. Exchanges routing tables with neighborsD. Calculates shortest pathE. Utilizes frequent periodic updatesAnswer: A, B, DExplanation:Link-state algorithms (also known as shortest path first algorithms) flood routinginformation to all nodes in the internetwork.
Each router, however, sends only the portionof the routing table that describes the state of its own links. In link-state algorithms, eachrouter builds a picture of the entire network in its routing tables. Distance vectoralgorithms (also known as Bellman-Ford algorithms) call for each router to send all orsome portion of its routing table, but only to its neighbors. In essence, link-statealgorithms send small updates everywhere, while distance vector algorithms send largerupdates only to neighboring routers.
Distance vector algorithms know only about theirneighbors.The primary advantage of link-state routing is that it reacts more quickly, and in abounded amount of time, to connectivity changes. Also, the link-state packets that aresent over the network are smaller than the packets used in distance-vector routing.Distance-vector routing requires a node's entire routing table to be transmitted, while inlink-state routing only information about the node's immediate neighbors are transmitted.Therefore, these packets are small enough that they do not use network resources to anysignificant degree.
The primary disadvantage of link-state routing is that it requires morestorage and more computing to run than distance-vector routing.Incorrect Answers:C, E: These are characteristics of distance vector routing protocols.QUESTION 481:Exhibit:Actualtests.com - The Power of Knowing640-802You work as a network technician at Certkiller .com. Study the exhibit carefully. Anetwork associate has configured OSPF with the command:Certkiller 2(Config-router)#network 192.168.12.64 0.0.0.63 area 0After completing the configuration, the associate discovers that not all interfaces areparticipating in OSPF.
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