Chapter 4

Question 1

What is the bandwidth rating

Answer 1

This is the number of bits per second that can be transmitted across a medium.

Question 2

What is Encoding

Answer 2

The method used to represent bits on a medium.

different network standards use different patterns of electrical or light pulses to represent a series of bits on the medium

Question 3

What is attenuation

Answer 3

This is the process of signal weakening to the point that the receiving device can no longer accurately read the information

Question 4

What is a cable segment

Answer 4

This is the length of cable between any two network devices (such as a NIC and a switch). Passive (unpowered) devices such as a wall jack are considered a part of the total cable segment length.

Question 5

What is electromagnetic interference (EMI)

Answer 5

a disturbance to the operation of an electronic cirucuit or its data, caused by devices that emit an electromagnetic field.

Question 6

What is Radio Frequency Interference (RFI)

Answer 6

Similar to EMI, but RFI is usually interference caused by strong broadcast sources (such as a nearby tv or radio station)

Question 7

What is crosstalk

Answer 7

This is interference one wire generates on another wire when both wires are in a bundle.

Question 8

Which media is susceptible to electronic eavesdropping

Answer 8

Copper wire.

Fiber optic carries light instead of electricity and is therfore not susceptible to this kind of eavesdropping.

Question 9

Cable grade is an inportant factor when deploying network media.

Cables ran between a false ceiling and the true celing must be ___ rated

UTP cabling is marked as one of two types, what are they?

Only one of the two types can only be used in building risers or in cable trays, which is it?

Answer 9

plenum

Communication Cable Rise (CMR), or Communication Cable Plenum (CMP)

CMR Communication Cable Riser

Question 10

Give a brief background of Coaxial Cable

Answer 10

once the predominant form of network cabling

Inexpensive and easy to instal

started to phase out in the early 1990’s

Still used primarily in connecting a cable modem to the wall outlet your cable tv/internet provider installs

Question 11

What are the two types of Twisted-Pair cables

What is the reason for the twists

Answer 11

The types are unshielded and shielded

The twists are necessary to improve resistance to corsstalk from wires and EMI from outside sources

Question 12

What type of cabling do most networks use

How many wires does it consist of

Answer 12

Unshielded twisted pair

4 pairs of insulted wires

Question 13

What is the purpose of the shielding in shileded twisted-pair cable?

Answer 13

to reduce cross-talk and interference

Question 14

What are RJ - 45 connectors

Answer 14

STP and UTP use registered jack 45 (RJ-45)

Most commonly used in patch cables, which are used to connect computers to hubs, switches, and RJ-45 wall jacks

Question 15

What is patch cable

Answer 15

short cable for connecting a computer to an RJ-45 wall jack or connecting a patch-panel port to a switch or hub

Can be made with inexpensive tools, two RJ-45 plugs and a length of TP cable

Question 16

What are patch panels

Answer 16

Used to terminate long runs of cable from where the computers are to the wiring closet (where the switches and hubs are)

Question 17

What are distribution racks

Answer 17

hold network equipment such as routers and switches, plus patch panels and rack mounted servers

Also called 19” racks because the upright rails are 19” apart

Question 18

What is structured cabling

Answer 18

specifies how cabling should be organized, regardless of the media type or network architecture

Question 19

Define work area

Answer 19

where workstations and other user devices are located

faceplates and wall jacks are installed in the work area

Question 20

What is horizontal wiring

Answer 20

This runs from the work area’s wall jack to the telecommunication closet

Wiring from the wall jack to the patch panel should be no longer than 90 meters

Question 21

What is a telecommunications closet

Answer 21

TC provides connectivity to computer equipment in the nearby work area

Typical equipment includes patch panels to terminate horizontal wiring runs, hubs and switches

A TC that houses the cabling and devices for work area computers is referred to as an intermediate distribution frame (IDF)

Question 22

What is an equipment room

Answer 22

this houses servers, routers, switches, and other major network equipment and serves as a connection point for backbone cabling

Question 23

What is a main distribution frame?

Answer 23

This is the name for an equipment room that’s the connection point betweein Intermediate Distribution Frames

Question 24

What is an intermediate distribution frame (IDF)

Answer 24

This is a Telecommunications Closet that houses cabling and devices for work area computers

Question 25

What is the main cross-connect for the entire network or it might serve as the connecting point for backbone cabling between buildings

Answer 25

The main distribution frame Each building has it's own

Question 26

What does backbone cabling interconnect

Answer 26

IDFs and MDFs it runs between floors or wings of a building and between buildings frequently fiber-optic cable but can also be UTP if the distance between TCs is less than 90 meters

Question 27

What is an entrance facillity

Answer 27

This is the location of the cabling and equipment that connects a corporate network to a third-party telecommunications provider This can also serve as an equipment room and the main cross-connect for all backbone cabling Where a connection to a WAN is made

Question 28

What is the Demarcation point

Answer 28

point where corporate LAN equipment ends and a third-party provider's equipment and cabling begins

Question 29

What are the two kinds of patch cables and what is the difference between then

Answer 29

Straight through cables which have the same wiring standards on both ends Crossover cables have a 568A standard on one end and a 568B standard on the other end

Question 30

What are medium dependent interface (MDI) devices or MDI crossed (MDI-X) devices

Answer 30

* MDI devices transmit on pins 1 and 2 and receive on pins 3 and 6 * PC NICs and routers are examples * MDI - X devices receive on pins 1 and 2 and transmit on pins 3 and 6 * Hubs and switches are examples

Question 31

Why two transmit and two receive wires?

Answer 31

One pair is for receive and one pair is for transmit. They are positive and negative to mitigate interference (crosstalk and noise)

Question 32

What is the composition of a fiber-optic cable

Answer 32

slender cylinder of glass fiber called the core surrounded by a concentric layer of glass called the cladding fiber is then jacketed in a thin transparent plastic material called the buffer

Question 33

What is a single-mode fiber (SMF)

Answer 33

Incldues a single, small-diameter fiber at the core (8microns) Generally works with laser-based emitters Spans the longest distances Used in higher-bandwidth applications

Question 34

What is Multimode fiber (MMF)

Answer 34

Larger diameter fiber at the core (50 and 62.5 microns) Costs less than SMF Works with lower-power light emitting diodes (LEDs) Spans shorter distances

Question 35

describe a Transceiver/access point (AP)

Answer 35

a transmitter/receiver device that must be installed to translate between wired and wireless networks includes an antenna and a transmitter to send and receive wireless traffic but also connects to the wired side of the network shuttles traffic back and forth between a network's wired and wireless sides

Question 36

What form do signals take in Wireless LAN transmission

Answer 36

waves in the Electromagnetic (EM) spectrum The frequency of the wave forms used for communication is measured in cycles per second, usually expressed as hertz (Hz) Lower-frequency transmissions can carry less data more slowly over longer disntaces, and higher-frequency transmissions can carry more data faster over shorter distances

Question 37

What are the most common frequencies for wireless data communication

Answer 37

Radio - 10 KHz to 300 MHz Microwave - 300 MHz to 300 GHz Infared - 300 GHz to 400 THz (terahertz)

Question 38

What are the four primary technologies that wireless LANs make use of for transmitting and receiving data?

Answer 38

Infrared Laser Narrowband (single-frequency) radio Spread-spectrum radio

Question 39

What are infrared (IR) signals

Answer 39

* These are infrared light beems to send signals between pairs of devices * Works well for LAN applications due to high bandwidth * Four main kinds of infrared LANs * Line-of-sight networks - require an unobstrcuted view between transmitter and receiver * Reflective wireless networks - broadcast signals from optical transceivers near devices to a central hub * Scatter infrared networks - bounch tranmsissions off walls and ceilings to deliver signals * Broadband optical telepoint networks - provide broadband services

Question 40

How do narrowband radio LAN technologies work?

Answer 40

use low-powered, two-way radio communication receiver and transmitter must be tuned to the same frequency No line of sight, just a mximum range (around 70m or 230ft) Walls or other solid objects can block signals interference from other radio sources is possible

Question 41

How does Spread-Spectrum LAN technology work

Answer 41

uses multiple frequencies simultaneously, improving reliability and reducing susceptibility to interferecnce (also makes eavesdropping more difficult) Two main kinds of spread-spectrum communications Frequency hopping - switches data between multiple frequencies at regular intervals Direct-sequence modulation - breaks data into fixed-size segments called chips and transmits the data on several different frequencies at the same time