Review Questions

1.	What are two benefits of using a link-state routing protocol? It uses the Hello protocol to establish adjacencies. It uses several components to calculate the metric of a route. Updates are sent only when changes occur in the network. It has a longer convergence time than distance-vector protocols.
2.	Which of the following metrics are used by IGRP by default when selecting a route? (Choose all that apply.) Bandwidth Load Delay Reliability
3.	Which of the following are not features of EIGRP? (Choose all that apply.) Incremental updates Only one route per destination Support for IP, IPX, and AT Hybrid distance-vector and link-state protocol Not a scalable protocol Hello protocol used to establish adjacencies
4.	By default, which of the following metrics are used by EIGRP when selecting a route? (Choose all that apply.) Load Bandwidth Reliability MTU Delay
5.	What is the routing algorithm used by RIP? Routed information Link together Link-state Distance-vector
6.	What is the routing algorithm used by IGRP? Routed information Link together Link-state Distance-vector
7.	What is the routing metric used by IP RIP? Counting to infinity Hop count TTL Bandwidth, reliability, MTU, delay, and load
8.	Which of the following protocols send out incremental updates by default? (Choose all that apply.) RIP IGRP OSPF EIGRP
9.	What does a metric of 16 hops represent in a RIP routing network? 16 ms Number of routers in the internetwork Number of hops 16 hops—unreachable
10.	What are hold-downs used for? To hold down the protocol from going to the next hop To prevent regular update messages from reinstating a route that has gone down To prevent regular update messages from reinstating a route that has just come up To prevent irregular update messages from reinstating a route that has gone down
11.	What is split horizon? Split horizon is information received from a router that can’t be sent back to that originating router. Split horizon is when you have a large bus (horizon) physical network and as a result, the routing protocol splits the traffic. Split horizon holds the regular updates from broadcasting to a down link. Split horizon prevents regular update messages from reinstating a route that has gone down.
12.	What is poison reverse? Poison reverse sends back the protocol received from a router as a poison pill, which stops the regular updates. Poison reverse is information received from a router that can’t be sent back to that originating router. Poison reverse prevents regular update messages from reinstating a route that has gone down. Poison reverse is when a router sets the metric for a down link to infinity.
13.	Which of the following are distance-vector protocols? (Choose all that apply.) IGRP RIP OSPF NLSP
14.	What is convergence time? The hold-down update time The time it takes for all routers to update their route table when a change takes place The time it takes for a packet to get from a destination host to a receiving host The time it takes to boot a router
15.	Which of the following protocols send out periodic updates by default? (Choose all that apply.) RIP IGRP OSPF EIGRP
16.	What are the metrics used by IPX RIP? (Choose all that apply.) Bandwidth Delay Hop count Ticks
17.	When do the IGRP timers remove a network route from the route table? When the update timer expires When the invalid timer expires When both the invalid and flush timers expire When both the update and flush timers expire
18.	What methods are used to stop routing loops with IGRP? (Choose all that apply.) Split horizon Spanning tree Infinite reply Poison reverse
19.	Which of the following statements are true about the routing process of a router? (Choose all that apply.) Path desirability is determined by routing metrics. All paths must be assigned by a network administrator. It is the process of determining the most desirable path through an internetwork. Once a router has determined a path for a transmission, any intermediary routers simply functions as repeaters.
20.	What happens during convergence time in an internetwork? The routers exchange manual updates. The routers exchange routing metrics. The routers exchange topology alerts. The routers exchange routing updates.

Answers

1.	A, C Adjacencies and link-state updates provide for much more reliable routing protocol updates.
2.	A, C Metrics of bandwidth and delay create a more defined routing update.
3.	B, E EIGRP uses DUAL to create multiple best route destinations and is scalable to large routing domains.
4.	B, E Load, reliability, and MTU can be configured as metrics for the EIGRP routing process.
5.	D RIP is a distance-vector routing protocol and uses hop count as a routing metric.
6.	D IGRP is a distance-vector routing protocol and uses bandwidth and delay as routing metrics.
7.	B RIP is a distance-vector routing protocol and uses hop count as a routing metric.
8.	C, D Both OSPF and EIGRP use incremental updates to notify neighbors of link-state changes.
9.	D RIP uses hop count as a metric, and 16 is deemed unreachable.
10.	B When routes have gone down, hold-downs prevent the routes from being reinstated until the next triggered update.
11.	A Split horizon is commonly used with distance-vector routing protocols to prevent route updates from being sent back the direction from which they came.
12.	D Poison reverse is used to prevent downed route updates from propagating through the network.
13.	A, B IGRP and RIP are both examples of distance-vector routing protocols.
14.	B Network convergence is the time from the first update to the final update when all routers have the same routing information.
15.	A, B Both RIP and IGRP use broadcast-type routing updates at specific intervals.
16.	C, D IPX RIP uses the hop count and tick metric for best path determination.
17.	C IGRP removes the downed route from the route table only after both the invalid and flush timers have expired.
18.	A, D IGRP uses both split horizon and poison reverse to prevent network routing loops.
19.	A, C The routing process is to determine the best path using the respective routing metric.
20.	D Convergence is the time in which route tables are processing updates.