A network can use a centralized or distributed model, and be designed as a client/server model or peer-to-peer.. logical Network Topologies A centralized network model has resources and
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36
SuMMAry oF ExAM oBJECTIvES
In this chapter, we discussed the fundamentals of networking, including what defines a network, and how networks came to be By providing an overview of these elements, we have provided a basic foundation for other topics covered throughout this book
We also looked at the various network types, topologies, and models available for a network A network can use a centralized or distributed model, and be designed as a client/server model or peer-to-peer In creat-ing this network, it will use one or more topologies, which is the physical layout of network components The topologies we covered in this chapter were bus, star, ring, mesh, and wireless Finally, the geographic scope of this network will determine what type of network you have LANs are small networks within a limited area of a few miles, MANs are within a metro-politan area, and WANs interconnect LANs over a wide area These char-acteristics define your network and will affect a wide variety of elements including security, media, and other features that make up your network
as a whole
ExAM oBJECTIvES FAST TrACK what Is a Network?
A computer network exists when two or more machines are
con-■
■
nected together, thereby allowing them to share data, equipment, and other resources
An internetwork is when two or more networks are connected
■
■
together, as in the case of the Internet
A network protocol is a set of rules used to control transmission
■
■
and reception of data on a networked computer TCP/IP is the default protocol used by the Internet and many current OSes, such
as Microsoft Windows and Novell NetWare
logical Network Topologies
A centralized network model has resources and administration
■
■
that are centrally located, while a decentralized network model has resources and administration that are distributed throughout the network
Trang 2A peer-to-peer network model has computers on a network acting
■
■
as equals, and acting as both clients and servers of the network
When one computer requests data or other services from another
computer, it acts as a client, while the other computer delivering
that data or service acts as a server
A client/server network model has dedicated servers that provide
■
■
services and data to requesting computers (clients) who are
autho-rized to access them
physical Network Topologies
The topology of a network is the physical layout of computers,
■
■
hubs, routers, cables, and other components Common topologies
include bus, star, ring, mesh, and wireless
All of the computers in a bus topology are connected together using
■
■
a single cable, which is called a trunk, backbone, or segment
In a star topology, computers aren’t connected to one another, but
■
■
are all connected to a central hub or switch
A mesh topology has multiple connections, making it the most
■
■
fault tolerant topology available
Ring topologies only allow one computer to have access to send
■
■
data on the ring, but provide equal access to the network
A point-to-point topology is any network that connects two hosts in
■
■
a dedicated fashion
A wireless topology broadcasts data over the air, so very few cables
■
■
are used to connect systems together
Network Types
LANs are small- to medium-size networks, and generally connect
■
■
network devices that are no more than a few miles of one another
WANs can span great geographical distances, and connect different
■
■
LANs together using high-speed solutions or telephone lines
A MAN is a group of LANs that are internetworked within a local
■
■
geographic area, which the IEEE defines as being 50 km or less in
diameter
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38
ExAM oBJECTIvES FrEquENTly ASKEd quESTIoNS
I am creating a home network that consists of one computer Q:
running an Apple iMac and another running Windows 2000 Professional Each of them has network adapters installed already I want to network them together, but can’t afford much
in the way of additional equipment What kind of network should
I create?
Peer-to-peer A peer-to-peer network is the simplest and least A:
expensive type of network you can create It doesn’t require a machine running more expensive server software, and can be created by configuring these machines to be networked together, and by connecting them to a hub (which is cheaper than a router) using network cabling Being that security isn’t an issue, P2P networks are ideal in these situations
My company wants to connect the LANs of an office in one city to Q:
an office in another city They want the fastest possible connection Which should I get?
T3 lines are the fastest, but they are also the most expensive T1 A:
and T3 lines are thousands of dollars a month, and may be more than your organization needs Before deciding on a particular con-nection for your network, try to determine what they will be using
it for, how often, and how much data will be transferred from one LAN to another
What is the most fault tolerant topology available?
Q:
The mesh topology is the most fault tolerant, because it uses A:
multiple connections to the network In this topology every computer is connected to every other computer, so if one cable breaks, the computer can continue using the network using another connection
My company is thinking of using wireless technology, but I’ve Q:
heard that hackers can access the data being transmitted using wireless Should this be a concern?
Network security should always be a concern Data being A:
transmitted using wireless technology can be protected using data encryption methods, which can prevent unwanted individuals from being able to decipher the data they capture from wireless signals
Trang 4What is the need for standards in networking?
Q:
Standards provide common methods and criteria for designing,
A:
developing, and manufacturing the hardware and software used
in networks It allows different devices to communicate with one
another, regardless of who manufactured them, so that networks
aren’t limited to using proprietary equipment It also provides best
practices, recommendations, and information that is necessary to
network communication (such as protocols that allow devices to
transfer data)
SElF TEST
You are creating a network for a small business with only four
1
employees Because employees often leave the office to visit clients,
a minimum of one person is in the office and using a computer at
any given time Currently there are two computers in the office,
but the company is willing to purchase more if needed Based on
this information, what is the minimum number of computers that
you’ll need to create a network?
A One
B Two
C Three
D Four
A new intranet has been created in your organization, and includes
2
an FTP site to download files and a news server for sharing
infor-mation The network is internetworked with a network belonging
to a subsidiary of the company The subsidiary’s network uses
Apple computers, and uses AppleTalk as a network protocol To
access the intranet, which of the following protocols would need to
be installed on your computer?
A IPX/SPX
B NWLink
C TCP/IP
D AppleTalk
The LAN used by your organization is on the single floor of a
3
building The network has servers and other resources that are kept
in a secure server room You are the only network administrator
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40
in the organization and have sole responsibility of managing these resources and administration of network security for all of the users who are distributed throughout the network What type of network model is being used?
A Centralized
B Decentralized
C Distributed
D Peer-to-Peer Your company’s network is on several floors of a building Because of
4
the amount of data being stored, there are three file servers, a Web server for the intranet, an e-mail server for internal e-mail, and a SQL server that is used for several databases that have been developed in house Because of security reasons, floppy disks and other devices to transfer or transmit data to and from the computer have been removed and aren’t permitted What type of network model is being used?
A Client/Server
B Peer-to-Peer
C MAN
D PAN Your company’s network spans three buildings that are within a mile
5
of one another Three servers are kept in a secure server room in the building where your office is located, while each other building has a server that is locked in a closet Users at each of these locations have been trained on how to replace the backup tapes in these servers and have the ability to give permissions for user accounts to print to specific printers in those locations You solely control other aspects
of security, inclusive to password requirements, and access to folders
on these servers What type of network model is being used?
A Centralized
B Decentralized
C P2P
D Peer-to-Peer
A company has hired you to create a network for their small
busi-6
ness Security isn’t an issue, and there isn’t enough money to hire
or train a permanent network administrator Users of the network routinely work on similar projects, and need to access one another’s data on a regular basis What type of network model will you use?
Trang 6B Peer-to-Peer
C Client
D Server
A company has multiple offices that are internetworked Office A
7
has a single computer that has the ability to dial into the
Internet, but isn’t connected to the other offices Office B is in
another part of the country from the other offices, but doesn’t
have its network interconnected to the other offices Office C and
D are in separate states, but have a dedicated connection between
them Office C has 20 computers that access each other’s
machines, and provide services and data to one another Office D
has 50 computers that log onto the network using a single server
Based on this information, which of the Offices are part of a LAN
and a WAN?
A Office A and B
B Office B and C
C Office C and D
D The entire network (Office A, B, C, and D)
An organization has offices in two countries Office A is a small
8
field office with two networked computers and is internetworked
with Office B that is across the road and has 10 networked
computers Because they are a subsidiary of the main company
and perform different services from the rest of the
organiza-tion, neither of these offices have been internetworked with
the other offices, and is awaiting Internet connectivity to be
provided next month Office C is another field office that has
a single computer, isn’t networked with other offices, and only
has an Internet connection Office D is the headquarters of the
company, has 100 network users who are awaiting Internet
connectivity to be added to the network, and has a network
connection to Office E in London, which is their European office
Based on this information, which of the offices is connected to
the largest WAN?
A Office A
B Office B
C Office C
D Office D
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42
A company wants to create a LAN between two networks in
9
different cities To connect them, you want to have the fastest possible connection to meet their needs Each network has mas-sive amounts of data being sent between floors of their existing networked building, and you determine that at maximum, 1 Mbps
of data will need to be transmitted during normal business hours Although they are a large business, and cost is not a major issue, they don’t want to waste money on getting a solution with a band-width that’s higher than they need What type of connection will you choose in connecting these networks?
A Dial-up modem
B ISDN
C T1
D T3
A company has several offices that are networked together across
10
the city Each of the sales representatives uses PDAs to keep track
of appointments with clients The company has just implemented
a new system where the appointments taken by receptionists are automatically uploaded to the PDAs whenever the sales staff enters the main reception area What types of networks are being used in this environment? Choose all that apply
A MAN
B SAN
C CAN
D PAN You have been hired by a company that uses a topology shown in
11
Figure 1.8 In looking at the physical layout of your network, which
of the following types of topologies is being used?
A Bus
B Star
C Mesh
D Ring
FIGurE 1.8
Trang 8You receive a call that the network is down In this network, all
12
of the computers are connected together using a single cable,
which they are connected to using T-Connectors Looking at the
situation, you find that there is no break through the trunk Which
of the following is most likely the cause of the problem?
A A failed network card
B One of the computers is turned off
C T-connectors are missing from the ends of the cable
D Terminators are missing from the ends of the cable
Your network uses cells to send and receive data to and from
com-13
puters This allows computers in different buildings to be networked
together, so they can access data from servers in either building
A topology map has been created, using circles to identify the areas
that computers can be placed to access the network Based on this
information, which of the following topologies is being used?
A Star
B Mesh
C Wireless
D Ring
You are training a new member of the IT Staff, and decide to
14
explain the topology of the existing network, shown in the
Figure 1.9 What topology is currently being used?
A Bus
B Star
C Mesh
D Ring
FIGurE 1.9
Trang 9ChApTEr 1: Network Fundamentals
44
Your network has 10 computers that are networked together using
15
a star topology Which of the following is a possible point of failure for this topology, which could bring down the entire network?
A Cable
B Network card
C T-Connector
D Hub
SElF TEST quICK ANSwEr KEy
B
1
C
2
A
3
A
4
B
5
B
6
C
7
C
8
C
9
A and D
10
A
11
D
12
C
13
C
14
D
15
Trang 10ExAM oBJECTIvES IN ThIS ChApTEr
INTroduCTIoN
In this chapter, we’ll take a look at what you will need to know about cable
connections and termination for the Network exam When working in
the field of networking, it’s nearly impossible to not come across physical
cabling Unless you have wireless media (covered in Chapter 4), you will
need some form of cabling, and need some form of endpoint, or
termina-tion, to your transmission media and a way for it to physically connect to a
device
This endpoint is called a connector, and it terminates the end of the
media, creating a way for it to connect to something else such as a patch
panel, switch port, or other connection This chapter shows you what you
need to know about connecting and terminating the most common forms of
cable in use today: twisted-pair cabling, coaxial cabling, and fiber optics The
understanding of transmission media types, connectors, and termination is
essential to being a networking professional In this chapter, we will learn
the fundamentals of cabling, the connectors used with them, and the most
common tools of the trade
Network Media