Chapter 12 Review Questions

Question 1

You have decided to establish a VoIP system in your home. Which of the following
devices is necessary to connect your analog telephone to your VoIP server?
a. Codec
b. IP-PBX
c. Softphone
d. ATA

Answer 1

ATA

Question 2

Skype, the popular Internet telephony service, provides a user with what type of
interface?
a. IP phone
b. Analog telephone
c. Softphone
d. IP-PBX

Answer 2

Softphone

Question 3

A company’s use of VoIP on its WAN to avoid long-distance telephone charges is
known as:
a. Toll bypass
b. WAN redirect
c. Fee gauging
d. Circuit redirect

Answer 3

Toll bypass

Question 4

Which of the following is the most popular signaling protocol used on traditional,
circuit-switched PSTN connections?
a. SIP
b. SS7
c. H.323
d. MEGACO

Answer 4

SS7

Question 5

Watching a YouTube video on the Web is an example of which of the following types
of video-over-IP services?
a. Videoconferencing
b. Streaming video
c. IP multicasting
d. IPTV

Answer 5

Streaming video

Question 6

In an IPTV system, which of the following functions does a set-top box perform?
a. Decodes video signals and issues them to a television
b. Determines the appropriate amount of bandwidth necessary to deliver a requested
video and adjusts the connection accordingly
c. Interprets multicast routing protocols to determine the most efficient means of
distributing video signals
d. Generates video content based on a subscriber’s channel selection

Answer 6

Decodes video signals and issues them to a television

Question 7

What type of video-over-IP service relies on full-duplex communication?
a. Webcasting
b. Streaming video
c. Videoconferencing
d. IPTV

Answer 7

Videoconferencing

Question 8

What protocol manages addressing for multicast groups?
a. IGMP
b. MGCP
c. MEGACO
d. H.245

Answer 8

IGMP

Question 9

Which of the following protocols would be used by a video bridge to invite a video
phone to join a videoconference?
a. MGCP
b. H.225
c. IGMP
d. RSVP

Answer 9

H.225

Question 10

Suppose your organization’s PSTN and VoIP systems are integrated, and that your VoIP
system adheres to architecture specified in H.323. Which of the following performs
translation between the PSTN’s signaling protocols and H.323 on your network?
a. H.323 terminal
b. H.323 gatekeeper
c. H.323 gateway
d. H.323 zone

Answer 10

H.323 gateway

Question 11

You are using a softphone to initiate a video call with a friend in another state. Which
of the following protocols is generating segments at the Transport layer of this
transmission?
a. ICMP
b. TCP
c. FTP
d. UDP

Answer 11

UDP

Question 12

What function does the H.225 protocol provide, as part of the H.323 VoIP
specification?
a. Handles call setup, call routing, and call termination
b. Controls communication between media gateways and media gateway controllers
c. Ensures that signals issued to an H.323 terminal are in a format that the terminal
can interpret
d. Indicates priority of each IP datagram

Answer 12

Handles call setup, call routing, and call termination

Question 13

In SIP, which of the following network elements maintains a database with network
address information for every SIP client?
a. Redirect server
b. Registrar server
c. Domain server
d. Proxy server

Answer 13

Registrar server

Question 14

Which of the following are reasons for choosing SIP over H.323? (Choose two.)
a. SIP is an older, more reliable standard.
b. SIP has limited functionality, which makes it more flexible.
c. SIP messages use fewer processing resources.
d. SIP includes QoS mechanisms that make it more dependable.
e. SIP supports a wider range of voice and video codecs.

Answer 14

SIP messages use fewer processing resources

SIP supports a wider range of voice and video codecs.

Question 15

Which of the following devices enable multiple media gateways to communicate?
a. VoIP router
b. IP-PBX
c. MGC
d. IP phone

Answer 15

MGC

Question 16

At what layer of the OSI model does RTP operate?
a. Transport
b. Presentation
c. Session
d. Application

Answer 16

Application

Question 17

What can RTCP do that RTP cannot?
a. Issue time stamps for every transmission
b. Assign sequence numbers to each packet in a transmission
c. Report on the degree of packet loss and delay in a connection
d. Modify each IP datagram to assign a priority level

Answer 17

Report on the degree of packet loss and delay in a connection

Question 18

How does RSVP help improve QoS?
a. It assigns a label to each IP datagram that will be read and modified by every router
in the data’s path.
b. It continually assesses the status of likely routes in the transmission’s path and
dynamically modifies IP datagrams as they’re issued with instructions for following
the best path.
c. It modifies the Priority field in each IP datagram so that high-bandwidth
applications are given precedence over low-bandwidth applications.
d. It establishes a path between the sender and receiver that is guaranteed to supply
sufficient bandwidth for the transmission.

Answer 18

It establishes a path between the sender and receiver that is guaranteed to supply sufficient bandwidth for the transmission.

Question 19

The Traffic Class field in an IPv6 datagram serves the same function as which of the
following fields in an IPv4 datagram?
a. TTL
b. DiffServ
c. RSVP
d. Padding

Answer 19

DiffServ

Question 20

On a VoIP network that uses the DiffServ QoS technique, which of the following makes
certain that a router forwards packets within a given time period?
a. Assured Forwarding
b. Superior Forwarding
c. Expedited Forwarding
d. Best-effort Forwarding

Answer 20

Expedited Forwarding