Ensurepass

CCNA Routing and Switching v3.0

 

QUESTION 161

Refer to the exhibit. What is the meaning of the output MTU 1500 bytes?

 

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A.

The maximum number of bytes that can traverse this interface per second is 1500.

B.

The minimum segment size that can traverse this interface is 1500 bytes.

C.

The maximum segment size that can traverse this interface is 1500 bytes.

D.

The minimum packet size that can traverse this interface is 1500 bytes.

E.

The maximum packet size that can traverse this interface is 1500 bytes.

F.

The maximum frame size that can traverse this interface is 1500 bytes.

 

Correct Answer: E

Explanation:

The Maximum Transmission Unit (MTU) defines the maximum Layer 3 packet (in bytes) that can be transmitted out the interface.

 

 

QUESTION 162

What is the default administrative distance of OSPF?

 

A.

90

B.

100

C.

110

D.

120

 

Correct Answer: C

Explanation:

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.

Default Distance Value Table

This table lists the administrative distance default values of the protocols that Cisco supports:

 

Route Source

Default Distance Values

Connected interface

0

Static route

1

Enhanced Interior Gateway Routing Protocol (EIGRP) summary route

5

External Border Gateway Protocol (BGP)

20

Internal EIGRP

90

IGRP

100

OSPF

110

Intermediate System-to-Intermediate System (IS-IS)

115

Routing Information Protocol (RIP)

120

Exterior Gateway Protocol (EGP)

140

On Demand Routing (ODR)

160

External EIGRP

170

Internal BGP

200

Unknown*

255

 

 

QUESTION 163

Which Layer 2 protocol encapsulation type supports synchronous and asynchronous circuits and has built-in security mechanisms?

 

A.

HDLC

B.

PPP

C.

X.25

D.

Frame Relay

 

Correct Answer: B

Explanation:

PPP: Provides router-to-router and host-to-network connections over synchronous and asynchronous circuits. PPP was designed to work with several network layer protocols, including IP. PPP also has built-in security mechanisms, such as Password Authentication Protocol (PAP) and Challenge Handshake Authentication Protocol (CHAP).

 

 

QUESTION 164

Refer to the exhibit. In the Frame Relay network, which IP addresses would be assigned to the interfaces with point-to-point PVCs?

 

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A.

DLCI 16: 192.168.10.1 /24

DLCI 17: 192.168.10.1 /24

DLCI 99: 192.168.10.2 /24

DLCI 28: 192.168.10.3 /24

B.

DLCI 16: 192.168.10.1 /24

DLCI 17: 192.168.11.1 /24

DLCI 99: 192.168.12.1 /24

DLCI 28: 192.168.13.1 /24

C.

DLCI 16: 192.168.10.1 /24

DLCI 17: 192.168.11.1 /24

DLCI 99: 192.168.10.2 /24

DLCI 28: 192.168.11.2 /24

D.

DLCI 16: 192.168.10.1 /24

DLCI 17: 192.168.10.2 /24

DLCI 99: 192.168.10.3 /24

DLCI 28: 192.168.10.4 /24

 

Correct Answer: C

Explanation:

With point to point PVC’s, each connection needs to be in a separate subnet. The R2-R1 connection (DLCI 16 to 99) would have each router within the same subnet. Similarly, the R3-R1 connection would also be in the same subnet, but it must be in a different one than the R2-R1 connection.

 

 

QUESTION 165

Refer to the exhibit. What is the meaning of the term dynamic as displayed in the output of the show frame-relay map command shown?

 

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A.

The Serial0/0 interface is passing traffic.

B.

The DLCI 100 was dynamically allocated by the router.

C.

The Serial0/0 interface acquired the IP address of 172.16.3.1 from a DHCP server.

D.

The DLCI 100 will be dynamically changed as required to adapt to changes in the Frame Relay cloud.

E.

The mapping between DLCI 100 and the end station IP address 172.16.3.1 was learned through Inverse ARP.

 

Correct Answer: E

Explanation:

Inverse Address Resolution Protocol (Inverse ARP) was developed to provide a mechanism for dynamic DLCI to Layer 3 address maps. Inverse ARP works much the same way Address Resolution Protocol (ARP) works on a LAN. However, with ARP, the device knows the Layer 3 IP address and needs to know the remote data link MAC address. With Inverse ARP, the router knows the Layer 2 address which is the DLCI, but needs to know the remote Layer 3 IP address.

When using dynamic address mapping, Inverse ARP requests a next-hop protocol address for each active PVC. Once the requesting router receives an Inverse ARP response, it updates its DLCI-to-Layer 3 address mapping table. Dynamic address mapping is enabled by default for all protocols enabled on a physical interface. If the Frame Relay environment supports LMI autosensing and Inverse ARP, dynamic address mapping takes place automatically. Therefore, no static address mapping is required.

 

 

QUESTION 166

What are three reasons that an organization with multiple branch offices and roaming users might implement a Cisco VPN solution instead of point-to-point WAN links? (Choose three.)

 

A.

reduced cost

B.

better throughput

C.

broadband incompatibility

D.

increased security

E.

scalability

F.

reduced latency

 

Correct Answer: ADE

Explanation:

IPsec offer a number of advantages over point to point WAN links, particularly when multiple locations are involved. These include reduced cost, increased security since all traffic is encrypted, and increased scalability as s single WAN link can be used to connect to all locations in a VPN, where as a point to point link would need to be provisioned to each location.

 

 

QUESTION 167

It has become necessary to configure an existing serial interface to accept a second Frame Relay virtual circuit. Which of the following procedures are required to accomplish this task? (Choose three.)

 

A.

Remove the IP address from the physical interface.

B.

Encapsulate the physical interface with multipoint PPP.

C.

Create the virtual interfaces with the interface command.

D.

Configure each subinterface with its own IP address.

E.

Disable split horizon to prevent routing loops between the subinterface networks.

F.

Configure static Frame Relay map entries for each subinterface network.

 

Correct Answer: ACD

Explanation:

For multiple PVC’s on a single interface, you must use subinterfaces, with each subinterface configured for each PVC. Each subinterface will then have its own IP address, and no IP address will be assigned to the main interface.

 

 

QUESTION 168

What are two characteristics of Frame Relay point-to-point subinterfaces? (Choose two.)

 

A.

They create split-horizon issues.

B.

They require a unique subnet within a routing domain.

C.

They emulate leased lines.

D.

They are ideal for full-mesh topologies.

E.

They require the use of NBMA options when using OSPF.

 

Correct Answer: BC

Explanation:

Subinterfaces are used for point to point frame relay connections, emulating virtual point to point leased lines. Each subinterface requires a unique IP address/subnet. Remember, you cannot assign multiple interfaces in a router that belong to the same IP subnet.

 

 

QUESTION 169

Which command allows you to verify the encapsulation type (CISCO or IETF) for a Frame Relay link?

 

A.

show frame-relay lmi

B.

show frame-relay map

C.

show frame-relay pvc

D.

show interfaces serial

 

Correct Answer: B

Explanation:

When connecting Cisco devices with non-Cisco devices, you must use IETF4 encapsulation on both devices. Check the encapsulation type on the Cisco device with the show frame-relay map exec command.

 

 

QUESTION 170

Which encapsulation type is a Frame Relay encapsulation type that is supported by Cisco routers?

 

A.

IETF

B.

ANSI Annex D

C.

Q9333-A Annex A

D.

HDLC

 

Correct Answer: A

Explanation:

Cisco supports two Frame Relay encapsulation types: the Cisco encapsulation and the IETF Frame Relay encapsulation, which is in conformance with RFC 1490 and RFC 2427. The former is often used to connect two Cisco routers while the latter is used to connect a Cisco router to a non-Cisco router. You can test with your Cisco router when typing the command Router(config-if)#encapsulation frame-relay ? on a WAN link. Below is the output of this command (notice Cisco is the default encapsulation so it is not listed here, just press Enter to use it).

 

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Note: Three LMI options are supported by Cisco routers are ansi, Cisco, and Q933a. They represent the ANSI Annex D, Cisco, and ITU Q933-A (Annex A) LMI types, respectively. HDLC is a WAN protocol same as Frame-Relay and PPP so it is not a Frame Relay encapsulation type.

 

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