Interconnecting Cisco Networking Devices Part 1 v3.0 (ICND1)

 

QUESTION 111

What information can be used by a router running a link-state protocol to build and maintain its topological database? (Choose two.)

 

A.

hello packets

B.

SAP messages sent by other routers

C.

LSAs from other routers

D.

beacons received on point-to-point links

E.

routing tables received from other link-state routers

F.

TTL packets from designated routers

 

Correct Answer: AC

Explanation:

Reference: http://www.ciscopress.com/articles/article.asp?p=24090&seqNum=4

 

Link state protocols, sometimes called shortest path first or distributed database protocols, are built around a well-known algorithm from graph theory,

E.W. Dijkstra’a shortest path algorithm. Examples of link state routing protocols are:

Open Shortest Path First (OSPF) for IP

The ISO’s Intermediate System to Intermediate System (IS-IS) for CLNS and IP DEC’s DNA Phase V

Novell’s NetWare Link Services Protocol (NLSP)

Although link state protocols are rightly considered more complex than distance vector protocols, the basic functionality is not complex at all:

1. Each router establishes a relationship–an adjacency–with each of its neighbors.

2. Each router sends link state advertisements (LSAs), some

3. Each router stores a copy of all the LSAs it has seen in a database. If all works well, the databases in all routers should be identical.

4. The completed topological database, also called the link state database, describes a graph of the internetwork. Using the Dijkstra algorithm, each router calculates the shortest path to each network and enters this information into the route table.

OSPF Tutorial

 

 

QUESTION 112

Refer to the exhibit. Which two statements are correct? (Choose two.)

 

clip_image002

 

A.

This is a default route.

B.

Adding the subnet mask is optional for the ip route command.

C.

This will allow any host on the 172.16.1.0 network to reach all known destinations beyond RouterA.

D.

This command is incorrect, it needs to specify the interface, such as s0/0/0 rather than an IP address.

E.

The same command needs to be entered on RouterA so that hosts on the 172.16.1.0 network can reach network 10.0.0.0.

 

Correct Answer: AC

Explanation:

This is obviously the default route which is set between the routers and since it is entered in such a manner that it ensures connectivity between the stub network and any host lying beyond RouterA.

 

 

 

 

 

QUESTION 113

Refer to the exhibit. The enterprise has decided to use the network address 172.16.0.0. The network administrator needs to design a classful addressing scheme to accommodate the three subnets, with 30, 40, and 50 hosts, as shown. What subnet mask would accommodate this network?

 

clip_image004

 

A.

255.255.255.192

B.

255.255.255.224

C.

255.255.255.240

D.

255.255.255.248

E.

255.255.255.252

 

Correct Answer: A

Explanation:

Subnet mask A i.e. 255.255.255.192 with CIDR of /26 which means 64 hosts per subnet which are sufficient to accommodate even the largest subnet of 50 hosts.

 

clip_image006

 

QUESTION 114

Refer to the exhibit. Given the output for this command, if the router ID has not been manually set, what router ID will OSPF use for this router?

 

clip_image008

 

A.

10.1.1.2

B.

10.154.154.1

C.

172.16.5.1

D.

192.168.5.3

 

Correct Answer: C

Explanation:

The highest IP address of all loopback interfaces will be chosen -> Loopback 0 will be chosen as the router ID.

 

 

QUESTION 115

Which two of these functions do routers perform on packets? (Choose two.)

 

A.

Examine the Layer 2 headers of inbound packets and use that information to determine the next hops for the packets

B.

Update the Layer 2 headers of outbound packets with the MAC addresses of the next hops

C.

Examine the Layer 3 headers of inbound packets and use that information to determine the next hops for the packets

D.

Examine the Layer 3 headers of inbound packets and use that information to determine the complete paths along which the packets will be routed to their ultimate destinations

E.

Update the Layer 3 headers of outbound packets so that the packets are properly directed to valid next hops

F.

Update the Layer 3 headers of outbound packets so that the packets are properly directed to their ultimate destinations

 

Correct Answer: BC

Explanation:

This is the basic function of the router to receive incoming packets and then forward them to their required destination. This is done by reading layer 3 headers of inbound packets and update the info to layer 2 for further hopping.

 

 

 

 

 

 

 

 

 

 

QUESTION 116

Refer to the exhibit. Why are two OSPF designated routers identified on Core-Router?

 

clip_image010

 

A.

Core-Router is connected to more than one multi-access network.

B.

The router at 208.149.23.130 is a secondary DR in case the primary fails.

C.

Two router IDs have the same OSPF priority and are therefore tied for DR election

D.

The DR election is still underway and there are two contenders for the role.

 

Correct Answer: A

Explanation:

OSPF elects one DR per multi-access network. In the exhibit there are two DR so there must have more than one multi-access network.

 

 

QUESTION 117

What does administrative distance refer to?

 

A.

the cost of a link between two neighboring routers

B.

the advertised cost to reach a network

C.

the cost to reach a network that is administratively set

D.

a measure of the trustworthiness of a routing information source

 

Correct Answer: D

Explanation:

Reference: http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094195.shtml

 

Administrative distance is the feature that routers use in order to select the best path when there are two or more different routes to the same destination from two different routing protocols. Administrative distance defines the reliability of a routing protocol. Each routing protocol is prioritized in order of most to least reliable (believable) with the help of an administrative distance value.

 

Administrative distance is the first criterion that a router uses to determine which routing protocol to use if two protocols provide route information for the same destination. Administrative distance is a measure of the trustworthiness of the source of the routing information. The smaller the administrative distance value, the more reliable the protocol.

 

 

QUESTION 118

Which IP address is a private address?

 

A.

12.0.0.1

B.

168.172.19.39

C.

172.20.14.36

D.

172.33.194.30

E.

192.169.42.34

 

Correct Answer: C

 

 

QUES
TION 119

Refer to the exhibit. If the resume command is entered after the sequence that is shown in the exhibit, which router prompt will be displayed?

 

clip_image012

 

A.

Router1>

B.

Router1#

C.

Router2>

D.

Router2#

 

Correct Answer: C

Explanation:

After resuming the telnet session by using the Enter key after it has bee
n suspended, it will resume back to the telnet session so it will be back to the router2>prompt.

 

 

QUESTION 120

A network administrator is trying to add a new router into an established OSPF network. The networks attached to the new router do not appear in the routing tables of the other OSPF routers. Given the information in the partial configuration shown below, what configuration error is causing this problem?

 

Router(config)# router ospf 1

 

Router(config-router)# network 10.0.0.0 255.0.0.0 area 0

 

A.

The process id is configured improperly.

B.

The OSPF area is configured improperly.

C.

The network wildcard mask is configured improperly.

D.

The network number is configured improperly.

E.

The AS is configured improperly.

F.

The network subnet mask is configured improperly.

 

Correct Answer: C

Explanation:

When configuring OSPF, the mask used for the network statement is a wildcard mask similar to an access list. In this specific example, the correct syntax would have been “network 10.0.0.0 0.0.0.255 area 0.”

 

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