Erouting v4.0 Chapter 10

Expect minimum percentage: 97.4%

1. Which algorithm is run by link-state routing protocols to calculate the shortest path to destination networks?
ans:
Dijkstra

2. What feature do modern link-state protocols provide to minimize processing and memory requirements?
ans:
splitting routing topologies into smaller areas

3. What is the final step in the link state routing process?
ans:
SPF computes best path to each destination network

4. Refer to the exhibit. Which statement correctly describes the path traffic would take from the 10.0.0.0/24 network to the 192.168.1.0/24 network if a link-state routing protocol was in use?
ans:
BOS -> ORL -> JAX -> ATL because this path is the lowest cost

5. Refer to the exhibit. What kind of information would be seen in an LSP sent from router JAX to router ATL?
ans:
cost of the link

6. Refer to the exhibit. When Router D is configured to use a link-state routing protocol and is added to the network, what is the first thing that it does to begin learning the network topology?
ans:
It learns about its directly connected networks when its interfaces reach the up state.

7. What two statements correctly describe the link state routing process? (Choose two.)
ans:
all routers in the area have link state databases
each router in the area floods LSPs to all neighbors

8. What speeds up convergence in a network using link-state routing?
ans:
updates triggered by network changes

9. Why is it difficult for routing loops to occur in networks that use link-state routing?
ans:
Each router builds a complete and synchronized view of the network.

10. What are two advantages of using a link-state routing protocol instead of a distance vector routing protocol? (Choose two.)
ans:
Each router independently determines the route to each network.
After the inital LSP flooding, they generally require less bandwidth to communicate changes in a topology.

11. To achieve network convergence, what three steps does each link state router take? (Choose three.)
ans:
build a Link State Packet (LSP) containing the state of each directly connected link
flood the LSP to all neighbors, who then store all LSPs received in a database
construct a complete map of the topology and compute the best path to each destination network

12. What two events will cause a link state router to send LSPs to all neighbors? (Choose two.)
ans:
whenever the network topology changes
upon initial startup of router or routing protocol

13. Which database or table must be identical on all link-state routers within an area in order to construct an accurate SPF tree?
ans:
link-state database

14. Which two routing protocols use Dijkstra’s shortest path first algorithm? (Choose two.)
ans:
IS-IS
OSPF

15. When are link-state packets sent to neighbors?
ans:
when a link goes up or down

16. Refer to the exhibit. What does JAX do with link-state packets from ORL?
ans:
sends out the individual link-state packets out the interface connected to BOS

17. A new network administrator is given the task of selecting an appropriate dynamic routing protocol for a software development company. The company has over 100 routers, uses CIDR and VLSM, requires fast convergence, and uses both Cisco and non-Cisco equipment. Which routing protocol is appropriate for this company?
ans:
OSPF

18. What action does a link-state router take immediately upon receipt of an LSP from a neighboring router?
ans:
floods the LSP to neighbors

19. Refer to the exhibit. If all routers and interfaces are configured to use a link-state routing protocol, from which routers will router D receive hello packets?
ans:
B and C

Erouting v4.0 Chapter 9

Expect minimum percentage: 100%

1. On a router running EIGRP, what database would maintain a list of feasible successors?
ans:
topology table

2. Refer to the exhibit. This is the debug output from 2 directly connected EIGRP routers. They are not forming an adjacency. What is the cause?
ans:
they have different autonomous-system numbers

3. Refer to the exhibit. Which command will advertise the 192.168.1.64/30 network but not the 192.168.1.32 network on router A?
ans:
network 192.168.1.64 0.0.0.3

4. What two actions will the EIGRP DUAL FSM take if a link to a network goes down? (Choose two.)
ans:
query neighbors for a new route
search topology table for a feasible successor

5. Refer to the exhibit. What is indicated by the P at the beginning of the topology entry?
ans:
the route is in a stable state

6. In which of the following tables does the EIGRP DUAL algorithm store the primary route to a destination? (Choose two.)
ans:
routing
topology

7. What information is maintained in the EIGRP topology database for a destination route? (Choose two.)
ans:
the feasible distance of the route
the route cost as advertised by the neighboring router

8. Which of the following statements describes the bounded updates used by EIGRP?
ans:
Partial updates are sent only to routers that need the information.

9. Host 192.168.1.66 in the network illustrated is unable to ping host 192.168.1.130. How must EIGRP be configured to enable connectivity between the two hosts? (Choose two.)
ans:
R1(config-router)# no auto-summary
R2(config-router)# no auto-summary

10. Which two statements describe characteristics of EIGRP? (Choose two.)
ans:
EIGRP is a distance vector routing protocol.
EIGRP supports classless routing and VLSM.

11. Refer to the exhibit. Based on the output of show ip eigrp neighbors, what are two possible problems with adjacencies between Router1 and Router2? (Choose two.)
ans:
The routers are configured with different EIGRP process IDs.
The serial interfaces for both routers are in different networks.

12. Refer to the exhibit. In the topology table, what do the numbers 3011840 and 3128695 represent?
ans:
the total metric for that network as advertised by the EIGRP neighbor

13. Refer to the exhibit. EIGRP is the only routing protocol enabled on this network. No static routes are configured on this router. What can be concluded about network 198.18.1.0/24 from the exhibited output?
ans:
Packets that are destined for 198.18.1.0/24 will be forwarded to 198.18.10.6.

14. Refer to the exhibit. All interfaces have been configured with the bandwidths that are shown in the exhibit. Assuming that all routers are using a default configuration of EIGRP as their routing protocol, what path will packets take from the 172.16.1.0/16 network to the 192.168.200.0/24 network?
ans:
A,B,E

15. By default, which two metrics are used by EIGRP to determine the best path between networks?
ans:
delay
bandwidth

16. Which term defines a collection of networks under the administrative control of a single entity that presents a common routing policy to the Internet?
ans:
autonomous system

17. Refer to the exhibit. The company is using EIGRP with an autonomous system number of 10. Pings between hosts on networks that are connected to router A and those that are connected to router B are successful. However, users on the 192.168.3.0 network are unable to reach users on the 192.168.1.32 network. What is the most likely cause of this problem?
ans:
The routers are not configured in the same EIGRP routing domain.

18. In the command router eigrp 20, what is the purpose of the number 20?
ans:
identifies the autonomous system number this EIGRP process will advertise

19. The show ip eigrp topology command output on a router displays a successor route and a feasible successor route to network 192.168.1.0/24. In order to reduce processor utilization, what does EIGRP do when the primary route to this network fails?
ans:
The backup route to network 192.168.1.0/24 is installed in the routing table.

20. What administrative distance would a router assign to a default route in EIGRP that is learned from a source external to the autonomous system?
ans:
170

21. Refer to the exhibit. Network 192.168.0.0/28 goes down. What type of packet does Router2 immediately send to Router1 and Router3?
ans:
unicast update packets to 192.168.1.1 and 192.168.2.1

Erouting v4.0 Chapter 8

Expect minimum percentage: 100%

1. Refer to the exhibit. The network administrator has discovered that packets destined for servers on the 172.16.254.0 network are being dropped by Router2. What command should the administrator issue to ensure that these packets are sent out the gateway of last resort, Serial 0/0/1?
ans:
ip classless

2. Refer to the exhibit. How many routes in this output qualify for use as ultimate routes?
ans:
7

3. The following entry is displayed in the routing table:

R 192.168.8.0/24 [120/2] via 192.168.4.1, 00:00:26, Serial0/0/1

What type of route is this?
ans:
a level 1 ultimate network route

4. Refer to the exhibit. The graphic contains partial contents of the routing table on router E. Router E is running version 12.3 of the IOS and is configured for default routing behavior. Router E receives a packet to forward. Which route in the routing table will be searched first and why?
ans:
172.16.0.0/25 because it is the first level 1 route

5. Refer to the exhibit. A packet destined for host 128.107.0.5/16 is processed by the JAX router. After finding the static route in the routing table that matches the destination network for this packet, what does the router do next?
ans:
performs a recursive lookup to find the exit interface used to forward the packet

6. A network is converged and the routing tables are complete. When a packet needs to be forwarded, what is the first criterion used to determine the best path in the routing table?
ans:
the route with the longest address and mask match to the destination

7. Refer to the exhibit. Router1 is running IOS version 12.2. What will the network administrator need to do so that packets for unknown child routes of 172.16.0.0/24 will not be dropped?
ans:
do nothing, ip classless is on by default

8. Refer to the exhibit. Router B receives a packet with a destination address of 10.16.1.97. What will router B do?
ans:
use the default route

9. Refer to the exhibit. What protocol was used to distribute the routing information for the network 172.16.1.4?
ans:
RIPv2

10. Refer to the exhibit. What subnet mask will Router1 apply to child routes of the 172.16.0.0/24 network?
ans:
255.255.255.0

11. A route to a destination network is learned from multiple routing protocols. What is used by a Cisco router to select the preferred route to the destination that will be installed in the routing table?
ans:
administrative distance

12. What occurs when no ip classless is implemented on the router?
ans:
The router will assume it has knowledge of all subnets in the network and will not search beyond child routes for a better match.

13. Refer to the exhibit. Router1 has been issued the ip classless command. What happens to packets destined to host 172.16.3.10?
ans:
forward out interface Serial0/0/1

14. Refer to the exhibit. With the ip classless command issued, what will router R2 do with a packet destined for host 172.16.4.234?
ans:
send packet out Serial 0/0/1

15. Refer to the exhibit. What parent network will automatically be included in the routing table when the three subnets are configured on Router1?
ans:
172.16.0.0/16

16. Refer to the exhibit. Which statement correctly describes this network?
ans:
There is at least one parent and one child route

17. Refer to the exhibit. What can be determined from this output?
ans:
All of the routes listed are network routes.

18. What determines if the router implements a classless route lookup process?
ans:
The command ip classless is enabled on the router.

Erouting v4.0 Chapter 7

Expect minimum percentage: 100%

1. Refer to the exhibit. If all routers are running RIP version 2, why is there no route for the 192.168.1.32/27 network?
ans:
Rip version 2 will auto summarize routes by default.

2. What are two reasons to implement RIP version 2 rather than RIP version 1? (Choose two.)
ans:
RIP version 2 supports VLSM.
RIP version 2 supports routing update authentication.

3. Refer to the exhibit. RIPv1 is configured as the routing protocol for the network that is shown. The following commands are used on each router:
router rip
network 10.0.0.0
network 172.16.0.0
When this configuration is complete, users on the LAN of each router are unable to access the remote LANs. Why?
ans:
RIPv1 is unable to route to discontiguous subnets of a major network.

4. Refer to the exhibit. What effect will the commands that are shown have on RIP updates for Router1?
ans:
Only version 2 updates are sent to 224.0.0.9.

5. Refer to the exhibit. A technician needs to add a new loopback interface to test routing functionality and network design. The technician enters the following set of commands on the router:
Sanford(config)# interface loopback1
Sanford(config-if)# ip address 192.168.6.62 255.255.255.252
Why does the router respond with an error?
ans:
The network address for Loopback1 overlaps with an already configured interface address.

6. What is the maximum network diameter permitted by the default metric of RIPv2?
ans:
15 hops

7. Refer to the exhibit. All routers are running RIP version 2. JAX is configured to just advertise the 10.0.0.0/24 network. CHI is configured to advertise the 172.16.0.0/16 network. A network administrator enters the commands shown in the exhibit. What changes will occur in this network?
ans:
The CHI router will install a route to the 192.168.0.0/16 network in its routing table.

8. Refer to the exhibit. What can be concluded from the output shown in the exhibit?
ans:
The no auto-summary has not been configured on this router.

9. Refer to the exhibit. All routers are running RIPv1. What changes will occur in the routing table of router B if a loopback interface with an address of 10.16.1.129/27 is configured on router B?
ans:
A connected route to the 10.16.1.128/27 network is added.

10. How are RIP v1 and RIP v2 similar to one another? (Choose three.)
ans:
They both use hop count as a metric.
They both have the same metric value for infinite distance.
They both use split horizon to prevent routing loops.

11. RIPv2 is the configured routing protocol on the routers in a network. The command Router(config-router)# no version 2 is entered on the routers. What effect does entering this command have on routing updates?
ans:
Version 1 and 2 updates will be received and the version 2 updates will not be sent.

12. A network administrator installed four new routers that are running RIPv2. Router1 is a boundary router in the RIPv2 network and has a default route configured. Once the network has converged, the network administrator enters Router1(config-router)# default-information originate on Router1. How will this affect the network?
ans:
propagates the default route to all routers in the network

13. Refer to the exhibit. The exhibited network contains a mixture of Cisco and non-Cisco routers. The command debug ip rip was entered on the JAX router. All routers are running the same version of RIP. Router CHI and Router ORL are not able to reach the 192.168.1.16/28 network. What is a possible solution to this problem?
ans:
Configure RIPv2 on routers.

14. Refer to the exhibit. Which command on which router will allow Router1 to learn about the 192.168.0.0/20 network?
ans:
Router2(config-router)# version 2

15. A network administrator has been told that the company IP address infrastructure must adhere to RFC 1918. What three IP address ranges from RFC 1918 could the administrator use on the network? (Choose three.)
ans:
10.0.0.0/8
172.16.0.0/12
192.168.0.0/16

16. Refer to the exhibit. Routers East and West are configured using RIPv1. Both routers are sending updates about their directly connected routes. The East router can ping the West router serial interface and West can ping the serial interface of East. However, neither router has dynamically learned routes from the other. What is most likely the problem?
ans:
VLSM is not supported by RIPv1.

17. Refer to the exhibit. Which command will allow Router2 to learn about the 192.168.16.0/28 network?
ans:
Router1(config-router)# network 192.168.16.0

18. What field was added to the RIP message header by RFC 1723 to add support for VLSM and CIDR?
ans:
subnet mask

19. What are two functions of the network command used when configuring routing protocols? (Choose two.)
ans:
identifies which networks will be included in the routing updates
determines which interfaces can send and receive routing updates

Erouting v4.0 Chapter 6

Expect minimum percentage: 100%

1. Refer to the exhibit. The network administrator wants to create a subnet for the point-to-point connection between the two routers. Which subnetwork mask would provide enough addresses for the point-to-point link with the least number of wasted addresses?
ans:
255.255.255.252

2. An additional subnet is required for a new Ethernet link between Router1 and Router2 as shown in the diagram. Which of the following subnet addresses can be configured in this network to provide a maximum of 14 useable addresses for this link while wasting the fewest addresses?
ans:
192.1.1.224/28

3. Refer to the exhibit. A network engineer is summarizing the two groups of routes on router R1 shown in the exhibit. Which summarization will work for all the subnets?
ans:
192.168.0.0/21

4. What is a supernet?
ans:
a summarization of serveral IP classful networks into one IP address range

5. In the network shown in the graphic, three bits were borrowed from the host portion of a Class C address. How many valid host addresses will be unused on the three point-to-point links combined if VLSM is not used?
ans:
84

6. What does VLSM allow a network administrator to do?
ans:
utilize multiple subnet masks in the same IP address space

7. Refer to the exhibit. The network administrator wants to minimize the number of entries in Router1’s routing table. What should the administrator implement on the network?
ans:
CIDR

8. Refer to the exhibit. A network technician enters the static route in R1 needed to reach network 10.1.1.0/24. A ping from the S0/0/0 interface on R1 to host B fails. The technician begins testing the network and has the following results:
1. pings from R1 to the S0/0/0 interface on R2....successful
2. pings from R1 to the Fa0/0 interface on R2....successful
3. pings from host B to hosts on the 10.1.1.0/24 network....successful
4. pings from host B to the Fa0/0 interface on R2....successful
5. pings from R2 to host B....successful.
What is the likely cause of the failure of the ping from R1 to host B?
ans:
The default gateway on host B is not correctly set.

9. Which three interior routing protocols support VLSM? (Choose three.)
ans:
OSPF
RIP v2
EIGRP

10. Refer to the exhibit. A network administrator needs to create two subnetworks from 10.0.0.0/8 for a router running RIPv2. The Admin subnet requires 120 hosts and the Sales subnet requires 58 hosts. The network administrator assigned 10.0.1.128/25 to the Admin subnet. The Sales subnet is given 10.0.1.192/26. What will be the result of this addressing scheme?
ans:
The subnets overlap and will be rejected by the router.

11. Which of the following are contained in the routing updates of classless routing protocols? (Choose two.)
ans:
32-bit address
subnet mask

12. A Class C address has been assigned for use in the network shown in the graphic. Using VLSM, which bit mask should be used to provide for the number of host addresses required on Router A, while wasting the fewest addresses?
ans:
/27

13. Refer to the exhibit. The number of required host addresses for each subnet in a network is listed in the exhibit. This number includes the host address requirements for all router ports and hosts on that subnet. After all device and router port address assignments are determined, what will be the total number of unused host addresses available?
ans:
29

14. What two advantages does CIDR provide to a network? (Choose two.)
ans:
reduced routing table size
reduced routing update traffic

15. A network administrator is tasked with dividing up a class C network among the QA, Sales, and Administration departments. The QA department is made up of 10 people, the Sales is made up of 28 people, and the Administration has 6. Which two subnets masks adequately address the QA and Sales departments? (Choose two.)
ans:
255.255.255.224 for Sales
255.255.255.240 for QA

16. Refer to the exhibit. In the network that is shown, the router interfaces are assigned the first address in each subnet. Which IP address would be usable for a host on one of the LANs in this network?
ans:
192.168.2.130/25

17. Refer to the exhibit. Which address is a broadcast address for one of the subnets that are shown in the exhibit?
ans:
192.168.4.15/29

18. Refer to the exhibit. What subnet mask will be applied by router B when it receives a RIPv1 update for the network 172.16.1.0?
ans:
24

19. Which of the following problems does VLSM help to alleviate?
ans:
the shortage of IP addresses

20. A router has a summary route to network 192.168.32.0/20 installed in its routing table. What range of networks are summarized by this route?
ans:
192.168.32.0 – 192.168.47.0/24