0

3.1 CCNA 4 - Voucher Exam

1
Which automatic process is started first whenever power
is applied to a Cisco router?
empties contents of NVRAM
looks for the configuration file
performs a POST
starts the operating system

2
Which of the following commands sets a condition to allow
packets through a named ACL?
adjust
apply
control
permit

3
Which of the following authentication processes provides
protection against playback attacks?
CHAP
DDI
PAP
TCP

4
Which command displays the active configuration of a router?
Router# show flash
Router# show configuration
Router# show running-config
Router# show startup-config

5
What is the default ISDN encapsulation used on Cisco ISDN routers?
SLIP
PPP
HDLC
VPP

6
How is spanning-tree path cost determined by default?
total hop count
sum of the costs based on bandwidth
dynamically determined based on load
individual link cost based on latency

7
Which command will successfully configure a router to use
PPP encapsulation on one of its links?
router> encapsulation ppp
router# encapsulation ppp
router(config)# encapsulation ppp
router(config-if)# encapsulation ppp

8
Which statement describes dynamic routing correctly?
Dynamic routing automatically adjusts for topology or
traffic changes.
Dynamic routing must always be used to reach a stub network.
Dynamic routing uses route information entered by an administrator.
Dynamic routing reveals everything known about an entire autonomous system.

9

The switches in the graphic are configured for VTP as shown.
Select the statements that correctly describe the operation of
these switches. (Choose two.)
A new VLAN can be added to Switch1 and that information
will be added only to Switch2.
An existing VLAN can be deleted from Switch2 and that
VLAN will be deleted from Switch1 and Switch4.
A new VLAN can be added to Switch4 and that information
will be added to Switch1, Switch2, and Switch3.
A new VLAN can be added to Switch1 and that information
will be added to Switch2 and Switch4.
A new VLAN can be added to Switch3 and that information
will be added to Switch1, Switch2, and Switch4.
An existing VLAN can be deleted from Switch4 and that
VLAN will be deleted from Switch1 and Switch2.

10
Which device uses logical addresses to interconnect networks
or subnetworks?
hub
layer 2 switch
router
bridge
repeater

11
Which device allows data communication to occur between VLANs?
bridge
hub
switch
router

12
Which of the following are types of EIGRP packets? (Choose three.)
hello
respond
DUAL
query
acknowledgement
holddown

13
Which Layer 4 protocol is connection-oriented and reliable?
ICMP
TCP
TFTP
UDP
HTTP

14
What is the purpose of the show cdp neighbors command?
to display a summary of the configurations of all directly
attached Cisco devices
to display information about all Cisco devices that are
directly connected to a local device
to display information about all Cisco networks in the WAN
to display addressing information about all remote routers
to display the names of all OSPF neighbors in the local area

15
Which connection modes are supported on a Frame Relay
subinterface? (Choose two.)
dynamic
multicast
multipoint
multipoint-to-point
point-to-point
static

16
A mid-sized company has five remote locations with 55 end
users at each location. The network administrator was assigned
two consecutive Class C networks. Which three interior routing
protocols will support this addressing scheme? (Choose three.)
RIP v1
RIP v2
EIGRP
OSPF
BGP

17
Which type of protocol is used between routers to communicate
and maintain tables?
non-routable
routable
routed
routing

18
The ISDN, Frame Relay, and HDLC encapsulations are defined
at which layer of the OSI model?
network
session
data link
transport
physical

19
Which layer of the OSI model provides negotiation of data
transfer syntax?
application
presentation
session
transport
network

20
What can be created by borrowing bits from the host portion
of an IP address?
extended IP addresses
additional IP addresses
segments
subnetworks
smaller collision domains

21
Which utility shows the route a packet takes to reach its destination?
netstat
ping
Telnet
traceroute

22

Refer to the graphic. This company was assigned a Class C network
address for its two sites. The network administrator subnetted
accordingly and configured each router with RIP. However, these
routers are unable to connect to each other. What could be the problem?
RIP cannot be used in place of a static route.
RIPv1 was configured instead of RIPv2.
RIPv2 was configured instead of RIPv1.
RIP does not support stub networks.

23
Which LMI types are available with Cisco routers?
ANSI, Cisco, HDLC
ANSI, Cisco, q933a
ANSI, Cisco, DLCI
Cisco, IETF, q933a

24
Which statements describe the operation of VLANs? (Choose two.)
All switch ports assigned to a VLAN are part of the same
collision domain.
All switch ports assigned to a VLAN are part of the same
broadcast domain.
Using VLANs to logically organize workgroups minimizes
latency in the network.
Members can be assigned to VLANs based on port ID,
MAC address, or protocol.
Multiple VLANs can be assigned to a single, Layer 3 network
address and routers can be used to route traffic between VLANs.

25

All routers shown in the graphic are part of the same OSPF area.
Which routers will PERTH engage in DR and BDR elections?
(Choose three.)
LONDON
PALMER
CAIRO
FRANKLIN

26
How is RIP configured on a router?
RIP is configured globally and then assigned an IP address and
subnet mask.
RIP is configured globally and then applied to each interface
that will participate in the RIP routing process.
RIP is configured individually on each interface that will
participate in the RIP routing process.
RIP is enabled globally and then networks are associated
with the RIP routing process.

27

In an effort to minimize traffic, an administrator decided to keep
web traffic from causing the ISDN link to come up by denying
WWW traffic to the 192.168.20.5 remote server. Two minutes
after making changes to the configuration as shown in the graphic,
the administrator notices that web traffic is still passing over the link.
What is the most likely cause of the problem?
The dialer-group has not been applied to outbound traffic.
The access-list is incorrectly configured.
Broadcasts are creating "interesting" traffic and keeping the link active.
The command ip access-group 128 out is missing from the bri0/0 interface.

28
Which of the following describe the Spanning Tree Protocol?
(Choose two.)
It prevents routing loops.
It prevents broadcasts in a switched network.
It operates at Layer 3.
It uses BPDUs to select the shortest path in a switched network.
It allows a router to load balance across redundant links.
It prevents switching loops.

29
Which of the following WAN services uses two data link layer
encapsulations, one for data and one for signaling?
ISDN
Frame Relay
ATM
FDDI

30
What is the length of a MAC address?
12 bits
24 bits
38 bits
48 bits

31
What is another term for latency?
backoff algorithm
hold-down timer
propagation delay
redundancy

32
Within a Frame Relay network, which methods are used by
switches to inform DTEs of congestion?
CCP and LMI
CIR and LATE
DLCI and SPID
FECN and BECN

33
For the purpose of forwarding packets, which protocol manages
communication between routers regarding available routes ?
DNS
ICMP
RIP
ARP
CDP
STP

34
What enables routers to learn of destination networks?
proxy ARP
CAM table exchanges
host name tables
routing protocols
DNS lookups

35
Which command will display the name of the Cisco IOS currently
running on a router?
show ip interfaces
show ip route
show cdp nei detail
show version

36
When connecting two routers from different vendors using a
dedicated point-to-point connection, which type of encapsulation
should be used?
Cisco
HDLC
IETF
PPP

37
Which fields are common to the TCP and the UDP segments?
(Choose two.)
source address
sequence number
acknowledgement number
options
checksum
destination port

38
How are VLANs configured?
by moving switches to different router ports
by changing switchports for each host on the segment
by physically moving equipment to a different network
through software
through hardware
automatically with a plug and play module

39

Which commands will configure the router ports with IP addresses
as shown in the diagram? (Choose three.)
R1(config)# interface s0
R1(config-if)# ip address 10.1.1.146 255.255.255.252
R1(config)# interface e0
R1(config-if)# ip address 10.1.7.254 255.255.252.0
R1(config)# interface s0
R1(config-if)# ip address 10.1.1.147 255.255.255.0
R1(config)# interface e0
R1(config-if)# ip address 10.1.4.0 255.255.252.0
R2(config)# interface e0
R2(config-if)# ip address 10.1.16.1 255.255.255.0
R2(config)# interface e0
R2(config-if)# ip address 10.1.31.254 255.255.240.0

40
Which mode will a router enter if it is unable to locate a valid startup configuration file during the boot process?
boot mode
config mode
RXBOOT mode
ROM monitor mode
setup mode
turnkey mode

41
What are the advantages of OSPF in comparison with RIP v2?
(Choose two.)
OSPF provides support for Classless Interdomain Routing but
RIP v2 does not.
OSPF may result in faster convergence, due to triggered updates.
OSPF's built-in features make it easy to design, implement, and troubleshoot.
OSPF routers build a complete view of the network, reducing the
potential for routing loops.
OSPF sends periodic link state advertisements to keep the link active.
OSPF routers have lower memory and processor requirements.

42
Which packet-switched WAN technologies are characterized by the use of Permanent Virtual Circuits (PVCs)?
Frame Relay and ISDN
Frame Relay and X.25
ISDN and X.25
ISDN only

43
Which statement is correct concerning routing and routed protocols?
A routed protocol allows the routers to communicate with other
routers and maintain tables for a routing protocol.
A routing protocol allows routers to communicate with other
routers and maintain tables for a routed protocol.
Routers only need to use routing protocols to work properly.
There is no difference between routed and routing protocols.

44
Which of the following are commonly used routing metrics?
(Choose three.)
ARP
hop count
window size
delay
load
media type

45
Which representations have the same meaning when representing
the subnet mask?
/10 and 255.224.0.0
/15 and 255.255.0.0
/21 and 255.255.248.0
/24 and 255.255.0.0

46
Which router parameters can be set from global configuration mode?
(Choose two.)
IP address
Telnet password
hostname
console password
subnet mask
enable secret password

47
How many host addresses may be assigned on each subnetwork
when using the 130.68.0.0 network address with a subnet mask of 255.255.248.0?
30
256
2046
2048
4094
4096

48
What is used to resolve known IP addresses to unknown MAC addresses?
ARP
DNS
DHCP
RARP

49
What are the effects of LAN segmentation using a switch?
(Choose three.)
dedicated bandwidth between source and destinations
enlarged collision domains
decreased broadcast domains
increased number of collision domains
increased latency in the network

50
Network broacast traffic from the Business Department is
needlessly reaching the Engineering Department LAN.
What can be done to contain this traffic within the Business
Department network while maintaining connectivity with
enterprise servers and the Internet? (Choose two.)
Establish a VTP domain to contain the extraneous traffic.
Provide greater bandwidth to the Engineering Department LAN.
Utilize full-duplex Ethernet on the Engineering Department LAN.
Place the business department on a separate subnet and route
between networks.
Change the switch IP address to an address on the Engineering
Department LAN.
Create separate VLANs and subnets for the two departments
and route between the two.

51
Which address does a bridge use to build its bridging table?
destination IP address
destination MAC address
source IP address
source MAC address

52
What are the functions of a Layer 2 Ethernet switch?
(Choose three.)
preventing broadcasts
increasing available bandwidth per user
decreasing the size of collision domains
isolating traffic among segments
routing traffic between different networks
decreasing the number of broadcast domains

53
In reference to the TCP/IP model, which protocol is used to
determine the network access layer address associated with a
known Internet layer address?
ARP
ICMP
IP
RARP
TCP
UDP

54
Which ISDN channel is used for call setup?
B
D
X
SS-7
PRI
BRI

55
Which of the following is the reference point between the NT1
and the phone company network?
R
S
T
U

56
How is the number 225 represented in binary?
11001111
11011011
11110011
11100001

57
What is the command syntax used to create a subinterface?
Router(config-if)# int s0.115 point-to-point
Router(config-if)# int s0 subinterface 115 point-to-point
Router(config-if)# subinterface 115 point-to-point
Router(config-if)# subinterface s0.115 point-to-point

58
Which item best describes the ping command?
It uses ICMP echo packets to verify connectivity at the
TCP/IP internet layer.
It checks for connectivity at the TCP/IP application layer.
It uses Time to Live (TTL) values to generate messages
from each router used along a path.
It verifies sliding window settings at the TCP/IP transport layer.

59
What are two authentication options supported by PPP?
(Choose two.)
clear text
PAP
CHAP
LCP
SLIP

60
An ISDN BRI line can be described as which of the following?
2B + D
2D + B
23B + D
23D + B

61
Which of the following is used for the delivery of EIGRP routing
information?
Reliable Transport Protocol (RTP)
Diffusing Update Algorithm (DUAL)
Protocol-Dependent Modules (PDMs)
Routing Table Maintenance Protocol (RTMP)

62
Which device connects four-wire ISDN subscriber wiring to
the conventional two-wire local loop?
NT1
NT2
TE1
TE2

63
Which OSI model layer is responsible for regulating the flow of
information from source to destination, reliably and accurately?
application
presentation
session
transport
network

64
Given a router that has already been configured, what is the
correct loading sequence when powering on?
bootstrap, RAM, operating system
bootstrap, configuration file, operating system
bootstrap, operating system, configuration file
operating system, configuration file, RAM

0

3.1 CCNA 4 - Practice Final

1
Which of the following LCP options can be configured for PPP?
(Choose three.)
CHAP
Stacker
IPCP
CDPCP
Multilink

2
ITU-T Q.921 specifies the use of which protocol for sending
control and signaling messages between the router and the
ISDN switch?
HDLC
IPCP
LAPB
LAPD
NCP
SS7

3
Which of the following describe functions of the Point-to-Point
protocol with regards to the OSI model? (Choose three.)
PPP uses Layer 3 of the OSI model to establish and
maintain a session between devices.
PPP operates at all layers of the OSI model.
PPP uses the data link layer to configure such
options as error detection and compression.
PPP provides a mechanism to multiplex several
network layer protocols.
PPP uses Network Control Protocols (NCP) to test and
maintain connectivity between devices.
PPP can be configured on both synchronous and
asynchronous serial interfaces.

4
Which of the following statements regarding point-to-point
subinterfaces are true? (Choose two.)
A point-to-point subinterface on one router must be
connected to a similar subinterface on a remote router.
Each point-to-point subinterface connection is
configured with its own subnet.
The DLCIs configured on the remote and local routers must
be the same for the PVC.
LMI frames are not transmitted through a subinterface.
Routing updates in point-to-point networks are
not subject to the split-horizon rule.

5

How will data be transmitted from the router to the ISP if
the router has the two links shown in the graphic?
Both links will transmit data at the same rate.
1544 bits can be transmitted simultaneously from the
router over the T1 line.
Both links will transmit bits one by one.
The 56K link will transmit a maximum of 53 bits at
the same time.

6
A network administrator is asked to design a system to
allow simultaneous access to the Internet for 250 users.
The ISP for this network can only supply five public IPs.
What can be used to accomplish this task?
routable translation
dynamic translation
static translation
port address translation

7
Which of the following statements are true about Frame Relay?
(Choose three.)
Frame Relay operation is defined by a series of ISO standards.
Frame Relay is a packet switched, connection-oriented,
wide area network service.
Frame Relay only supports point-to-point connections.
A router can be considered as data terminal equipment
(DTE) in a frame relay system.
Frame Relay is a cell switched, connection-oriented, wide area
network service.
Frame Relay networks use a subset of the HDLC
protocol to carry information.

8
Why would data frames be discarded in a Frame Relay network?
(Choose two.)
The frame contains an incorrect IP address.
An error has been detected in computing the
frame check sequence.
There is not enough bandwidth dedicated for the data
contained in the frame.
Data is transmitted at a rate greater than the access speed.
The frame contains an incorrect DLCI.

9

Which of the following can be concluded from the router output
displayed in the graphic? (Choose two.)
The local DLCI number of this PVC is 100.
The interface has been configured for subinterfaces and this
map is for subinterface 0.
Inverse ARP has determined the remote ip address
as 10.140.1.1.
The LMI type is ANSI (0x64).
There is currently no congestion on the link.

10
When planning simple WAN connections for a small company,
which feature of the three layer hierarchical model makes it a
good choice for the WAN topology.
It provides for redundancy.
It allows for easy WAN expansion in case of company growth.
It is less expensive.
It provides faster connection time.
It provides less latency and jitter.

11

The command output shown in the graphic was taken from
a Cisco 806 broadband router. Which kind of address
translation is in effect on this router?
static
dynamic
overload
private
public

12
A network administrator has been asked to provide the
network in the United States with an ISDN WAN link.
The router available to provide the WAN connection is a
non-modular Cisco router with two serial connections.
What must be done to adapt one of the serial interfaces
of this router for the ISDN connection?
Nothing. The router is already suitable.
Purchase a BRI WAN interface card to install in the router.
Purchase a U interface to install in the router.
Purchase a TA/NT1 device to install on the router.

13
How does Frame Relay technology process frames that
contain errors? (Choose two.)
Frame Relay services depend on the upper
layer protocols to handle error recovery.
It requires the receiving device to request that the
sender retransmit erroneous frames.
FECN, BECN, and DE bits are set in the frames to
minimize errors.
The receiving device drops any frames that
contain errors without notifying the sender.
The frame relay switch notifies the sender that errors
were detected.

14
Which statements about DHCP are true? (Choose three.)
DHCP uses TCP.
DHCP uses UDP.
DHCP sends messages to the server on port 67.
DHCP sends messages to the server on port 68.
DHCP sends messages to the client on port 67.
DHCP sends messages to the client on port 68.

15
Which command configures the SPID on the first B
channel of an ISDN interface?
Router(config)# isdn spid0 spid-number [ldn]
Router(config)# isdn spid1 spid-number [ldn]
Router(config-if)# isdn spid0 spid-number [ldn]
Router(config-if)# isdn spid1 spid-number [ldn]

16

Which command would produce the output shown in the graphic?
show ip dhcp server statistics
show ip dhcp binding
debug ip dhcp server events
debug ip dhcp binding

17
Which commands can be used to identify which DLCIs are
active? (Choose two.)
show frame-relay map
show frame-relay lmi
show frame-relay pvc
show frame-relay interface
show interfaces
show ip route

18
When PPP authentication is enabled, which of the following
may be checked before establishing a PPP link between
two devices? (Choose two.)
the enable password on the remote device
the ip host configuration on the remote device
the security server database for the username
and password of the remote device
the hostname and enable password on the local device
the local database for the username and password
of the remote device

19
Which of the following are supported by a BRI interface on a
router? (Choose two.)
Two independent channels that can carry analog
data with a bandwidth of 64 KHz.
A single 128 Kbps digital bearer channel.
Two multiplexed channels carrying digital data.
A single 64 Kbps signaling channel.
A multiplexed data channel that can only handle SS7 information.
A 16 Kbps delta channel used for signaling purposes.

20

An administrator consoled into the Jelly router needs to
telnet to the Butter router. What DLCI will the Jelly router
place in the frame to perform this operation?
110
115
220
225

21

What is placed in the address field of a frame that will travel
from the DC office of ABC company to the Orlando office?
MAC address of the Orlando router
MAC address of the DC router
192.168.1.25
192.168.1.26
DLCI 100
DLCI 200

22
The WAN connection for a nationwide company with 250
offices must support constant connections to core layer
services for file sharing, and occasional Internet access.
Which combination of WAN technologies will meet these
needs with minimum expense?
Frame Relay PVC for Internet access and ATM for file
server access
Frame Relay PVC for Internet access and ISDN for file
server access
ISDN for Internet access and X.25 for file server access
ISDN for Internet access and Frame Relay PVC for file
server access

23
What does a DLCI of 0 indicate about a frame? (Choose two.)
This is the first data frame sent by the router.
This is a management frame.
The encapsulation type is Cisco.
The encapsulation type is IETF.
The LMI type is Ansi or q933a.
The LMI type is Cisco.

24
A company needs a WAN connection that is capable of
transferring voice, video, and data at a minimum data
rate of 155 Mbps. Which WAN connection is the best choice?
X.25
DSL
ATM
ISDN BRI
ISDN PRI

25
What are three features of the CHAP protocol? (
Choose three.)
exchanges a random challenge number during
the session to verify identity
sends authentication password to verify identity
prevents transmission of login information in
plain text
disconnects the PPP session if authentication fails
initiates a two-way handshake

26
Which of the following devices is used to establish the
communications link between the customer equipment
and the local loop for digital lines?
terminal adapter
modem
CSU/DSU
PBX switch
ISDN switch
Frame Relay Switch

27
Which command would be used to exclude the IP address
192.168.24.5 from the DHCP address pool on a router?
Router(dhcp-config)# ip dhcp excluded-address 192.168.24.5
Router# ip dhcp excluded-address 192.168.24.5
Router(config-excluded)# ip dhcp excluded-address 192.168.24.5
Router(config)# ip dhcp excluded-address 192.168.24.5
Router(config)# excluded-address 192.168.24.5
Router(dhcp-config)# excluded-address 192.168.24.5

28
A router needs to forward a message received from a host.
How does the router identify the correct VC to forward the
message? (Choose two.)
The router forwards the frame to all ports in the network
and learns the address from the reply frame.
The destination host IP address is embedded in the DLCI.
The router searches Inverse ARP tables for maps of
DLCIs to IP addresses.
A table of static mappings can be searched.
The router broadcasts a request for the required IP address.

29
Which of the following switching types will allow the
communication devices in the provider's network to
be shared and only allocated to an individual subscriber
during data transfer?
circuit-switched
packet-switched
frame-switched
dedicated-switched lines
lease-switched

30
Which of the following IP addresses are defined by
RFC 1918 as private addresses? (Choose three.)
192.168.146.0/22
172.10.25.0/16
172.31.0.0/16
20.0.0.0/8
10.172.92.8/29

31
Which of the following describes the PAP protocol? (Choose two.)
sends unencrypted authentication passwords
performs a three-way handshake
allows repeated login attempts
uses the remote router hostname to verify identity
sends a random challenge throughout the session

32
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

33
Which statement explains why basic DSL is an unpopular
WAN connectivity choice for enterprise computer
departments that support home users?
DSL offers insufficient bandwidth to home users.
DSL requires the installation of new cables, which is not
always possible for home users.
DSL dialup connection time is too slow for business use.
DSL has limited geographical availability.

34
Which of the following are functions of the Local Management
Interface used in Frame Relay networks? (Choose three.)
exchange information about the status of
virtual circuits
map DLCIs to network addresses
provide flow control
provide error notification
provide congestion notification
send keepalive packets to verify operation of the PVC

35

An ISDN router is configured for DDR as shown in the
graphic to provide Internet connectivity for the company.
Immediately after a user in the company attempts opens
a web browser to connect to the Internet, another user in
the company tries to download a file using FTP.
What will happen? (Choose two.)
The user that opened the browser will connect
to the Internet because the DDR link will consider
this traffic interesting.
The Internet user will be disconnected because the FTP
data will cause the DDR link to shut down.
The DDR link will allow the FTP traffic because it is
interesting.
The DDR link will not allow the FTP traffic because it
is not interesting.
The FTP connection will fail because the DDR link is
already in use for the Internet connection.
The FTP connection will succeed because the
web user already opened the DDR link.

36
Which command will provide for CHAP authentication if
the hostname on a challenging router is tampa with a
password of florida?
username tampa password florida
username tampa florida
hostname tampa password florida
hostname tampa florida

37
Which of the following is a function of a DCE device?
determines the next-hop address for a packet
multiplexes signals from several sources
adapts information for use on a service provider's network
used to directly connect two DTEs to simulate a WAN network

38
Which operating systems support multiuser capability?
(Choose three.)
Linux
Windows 98
Windows ME
Windows XP
Windows 2000

39
Why was NAT created? (Choose two.)
to create firewalls on routers
to conserve IP addresses
to translate domain names into IP addresses
to map network addresses to the corresponding data
link address
to hide internal addresses from external devices

40
Which of the following terms describes a device that will put
data on the local loop?
DLCI
CO
DCE
DTE
PRI
BRI

41
How many separate B channel circuits can be provisioned on a
PRI interface that uses a T1 line for connectivity?
2
16
23
24
30
128

42

The LAN attached to the Ethernet interface of the Raleigh router
shown in the graphic is addressed with private IP addresses.
If one public IP is assigned to the company, which commands
could be used in a configuration that allows all devices with
private IPs in this network to access the Internet? (Choose two.)
ip nat inside source list 1 interface serial0 overload
ip nat outside source list 1 interface serial0 overload
ip nat inside serial0
ip nat inside source list 1 pool Raleigh overload
ip nat inside Raleigh overload
ip inside nat source list 1 interface serial0 Raleigh

43

Which of the following describes the WAN devices and cabling
shown in the graphic? (Choose two.)
A null-modem cable is used between RouterD and DeviceC
for connectivity.
A DB-25 or DB-9 serial cable is connected to interface S0/0 of
RouterA.
DeviceB and DeviceC are DCE devices.
The same encoding scheme must be used by DeviceB
and DeviceC.
A synchronous serial connection exists between DeviceB and
DeviceC.

44
Which of the following are commonly used as Data
Communications Equipment? (Choose two.)
modem
router
CSU/DSU
ISDN Switch
Frame Relay Switch

45
What does the command debug isdn q921 display?
exchange of call setup and teardown messages
PAP and CHAP authentication traffic
Layer 2 messages on the D channel
protocol errors and statistics
Layer 2 messages on the B channel

46
A technician is testing the functionality of a recently installed
router. The technician is unable to ping the serial interface of
a remote router. The technician executes the
show interface serial0/0
command on the local router
and sees the following line in the output:

Serial0/0 is up, line protocol is down

What are possible causes for this command output? (Choose three.)
remote CSU/DSU failure
serial cable missing
interface shutdown
keepalives not being sent
clocking signal missing