CCNA 4 Module 4 V3.1 Answers

1. Which of the following correctly describes ISDN BRI? (Choose three.)

two 64 kbps B channels and one 16 kbps D channel

B channel is suitable for voice data

uses in-band signaling

uses out-of-band signaling

offers the equivalent of a T1/E1 connection

twenty-three 64 kbps B channels and one 16 kbps D channel


2. Which of the following is considered out-of-band signaling?

using a frequency outside of the rated bandwidth for transmission

transmitting data over a control channel

using a separate channel for control signals

transmitting control signals over a data channel


3. A network administrator is troubleshooting ISDN connectivity. The administrator suspects the problem lies with the authentication protocol. What command should the administrator use to view the authentication process between the router and the ISDN switch?

debug pap authentication

debug chap authentication

debug ppp authentication

debug isdn authentication


4. Which router command would be used to enter the mode for configuring a T1 PRI connection?

Router(config)# controller t1 {slot/port}

Router(config)# interface pri t1 {slot/port}

Router(config)# interface pri {slot/port} t1

Router(config)# controller {slot/port} t1



CCNA 4 Module 4 V3.1 Answers (1)
The network administrator of XYZ company needs to configure a new ISDN router. After entering the commands shown in the graphic, the administrator tries to access the Internet but the ISDN connection does not open. If the service provider verifies that the problem is with XYZ's configuration, what is a possible cause of the problem?

The dialer map is configured incorrectly.

The encapsulation type is configured incorrectly.

The dialer group is configured incorrectly.

The ACL is configured incorrectly.

The isdn switch-type command needs to be configured globally.


6. Which of the following protocols can be used to encapsulate data traffic sent from a router BRI interface? (Choose two.)

Link Access Protocol - Data

High-Level Data Link Control

Logical Link Control

Serial Data Link Control

Point to Point protocol

Binary Synchronous Control protocol



CCNA 4 Module 4 V3.1 Answers (2)
A small company uses an ISDN WAN link to transfer e-mail to remote sites. What command would the administrator use to determine if the ISDN link is up?

show isdn status

show isdn active

show dialer

show interface bri0/0

debug isdn active


8. Which command configures an ISDN interface to use a switch type which is different from that used on other interfaces on the router?

Router(config)#switch-type switch-type

Router(config-if)#switch-type switch-type

Router(config)#isdn switch-type switch-type

Router(config-if)#isdn switch-type switch-type


9. Which of the following is essential for all ISDN BRI interface configurations?

ISDN switch type

line encoding technique

line framing method

local directory number

service profile identifier


10. You have just taken delivery of a new US standard Cisco 2620 router that includes a BRI "U" interface? Which of the following describes how this router will be connected in the ISDN network?

An external terminal adapter (TA) must be attached to the router for connectivity.

An NT1 must be connected to the router for connectivity.

The router is a TE1 device and is ready to connect to the provider's network.

The router is a TE2 device and requires both a TA and NT1 for connectivity.


11. What must be configured for an ISDN PRI connection? (Choose three.)

ISDN switch type

Service Profile Identifier (SPID)

Dial-on-Demand Routing (DDR)

PRI group time slot

T1/E1 controller, framing type and line coding



CCNA 4 Module 4 V3.1 Answers (3)
A network administrator is troubleshooting an ISDN connectivity problem. Users are complaining they cannot connect to the Internet. The network administrator suspects the ISDN connection attempt is timing out before a connection can be established. What command would the network administrator use to determine what the "wait for carrier" timeout value is set to?

show isdn status

show isdn active

show dialer

show interfaces bri0/0

debug isdn q931

show ISDN interfaces


13. What is a reason why static routes are preferred over dynamic routes for DDR to operate on an ISDN interface?

An ISDN interface will not allow dynamic routing updates that use broadcast technology.

A dynamic route will take precedence over a static route because of its lower administrative distance.

Dynamic routing can never be considered interesting traffic by default.

Dialer-list configuration does not support dynamic routing.

Dynamic routes may cause the ISDN connection to dial constantly to transmit updates.


14. Which of the following describes the use of a SPID? (Choose two.)

selects the ISDN switch type

identifies the line configuration of the BRI service

allows multiple ISDN devices to share the local loop

designates whether a device is a TE1 or TE2

allows ISDN broadcasts


15. Which command is used within an existing ISDN network to display current call information, including the called number?

show isdn status

show isdn active

show interfaces bri0/0

show ip interfaces


16. Which of the following are true of ISDN routers configured with dialer profiles? (Choose two.)

They do not use ACL to define interesting traffic.

Their B channels can be configured with different subnets and encapsulation types.

Their BRI interfaces can belong to multiple dialer pools.

They use PPP only.

They can only use the CHAP authentication protocol.


17. A network administrator in Europe has been asked to provide the network with an ISDN WAN link. The router available to provide the WAN connection is a non-modular Cisco router with an S/T interface. What further equipment will be provided by the ISDN service provider for the ISDN connection?

Nothing. The router is already suitable.

BRI WAN interface card to install in the router

an external NT1 to terminate the local loop

a TA/NT1 device to install on the router


18. Why must routers be configured to specify the ISDN switch type?

Switches use various implementations of Q.931.

The IOS of most routers lacks the ability to autosense the switch.

The switch must know what type of router it is communicating with.

The Layer 3 connection between the terminal equipment and the ISDN switch is not standardized.

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