Pass4sure 300-101 Question Answer

What additional configuration statement should be included on router R4 to advertise a default route to its neighbors?

Refer to the exhibit.

EIGRP has been configured on all routers in the network. What additional configuration statement should be included on router R4 to advertise a default route to its neighbors?

A.R4(config)# ip route 0.0.0.0 0.0.0.0 10.1.1.1

B.R4(config)# ip default-network 10.0.0.0

C.R4(config-router)# default-information originate

D.R4(config)# ip route 10.0.0.0 255.0.0.0 10.1.1.1

Answer B

Explanation:

Unlike the ip default-gateway command, you can use ip default-network when ip routing is enabled on the Cisco router. When you configure ip default-network the router considers routes to that network for installation as the gateway of last resort on the router. For every network configured with ip default-network, if a router has a route to that network, that route is flagged as a candidate default route.Gateways of last resort selected using the ip default-network command are propagated differently depending on which routing protocol is propagating the default route. For IGRPand EIGRP to propagate the route, the network specified by the ip default-network command must be known to IGRP or EIGRP. This means the network must be an IGRP- or EIGRPderived network in the routing table, or the static route used to generate the route to the network must be redistributed into IGRP or EIGRP, or advertised into these protocols using the network command. In this case, the 10.0.0.0 network is indeed being advertised via EIGRP.

Reference:

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094374.shtml#ipnetwork

What is the solution?

Refer to the exhibit.

Router RTA is the hub router for routers RTB and RTC. The Frame Relay network is configured with EIGRP, and the entire network is in autonomous system 1.However, router RTB and RTC are not receiving each other’s routes. What is the solution?

A.Check and change the access lists on router RTA.

B.Configure the auto summary command under router eigrp 1 on router RTA.

C.Configure subinterfaces on the spoke routers and assign different IP address subnets for each subinterface.

D.Issue the no ip split horizon command on router RTA.

E.Issue the no ip split horizon eigrp 1 command on router RTA.

F.Configure a distribute list on router RTA that allows it to advertise all routes to the spoke
routers.

Answer:E

Explanation:

Split horizon controls the sending of EIGRP update and query packets. When split horizon is enabled on an interface, these packets are not sent for destinations for which this interface is the next hop. This reduces the possibility of routing loops.By default, split horizon is enabled on all interfaces.

Split horizon blocks route information from being advertised by a router out of any interface from which that information originated. This behavior usually optimizes communications among multiple routing devices, particularly when links are broken. However, with nonbroadcast networks (such as Frame Relay and SMDS), situations can arise for which this behavior is less than ideal. For these situations, you may want to disable split horizon.In this example, routes received by RTB and RTC are not being sent back out the same serial interface on RTA, so they are not receiving each other’s routes. Disabling Split horizons on interface S0/0 on RTA will fix this issue.