Chapter 19
Networks
1
What’s Inside and on the CD?
• In this chapter you’ll learn:
– Basic network terminology
– To identify network components
– About advantages and disadvantages of networks
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What is a network?
• A Network is collection of devices with the ability to
communicate with each other
• A computer network, or network, consists of two or more
computers connected to allow information and devices to
be shared
• Communications protocol is a set of rules for
transmitting and receiving data from one network device to
another
• Three popular network standards are Ethernet, Wi-Fi, and
Bluetooth
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What is a network?
• A LAN (local area network) connects personal computers
within a very limited geographical area
• A WAN (wide area network) covers large geographical
area and consists of several smaller networks
• An Intranet is type of LAN
– Like the Internet, uses Internet technology
– Unlike the Internet, an intranet is maintained by a
private business or organization, and access is limited
to employees
– Can be expanded into an extranet that uses public
telephones and computer networks to share data
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What are the components of a local
area network?
• Network components include
– Computers and peripheral devices used for input and
output
– Specialized computers used to store and distribute
data
– Network devices
– Communications software
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What are the components of a local
area network?
• A network connection point is referred to as node and
contains:
– Computer
– Peripheral device
– Network communication device
– Home entertainment equipment
– Network-ready printer
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What are the components of a local
area network?
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What are the components of a local
area network?
• To connect to a LAN, a device requires network circuitry
– An Ethernet adapter connects a computer to network
cabling
– A Wi-Fi adapter transmits wireless signals
• Communications software formats and packages data
for transport
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What are the components of a local
area network?
• In an ad hoc network, network data can travel directly
from one device to another
• More typically, computer networks incorporate a central
device to handle communications
– Hubs
– Switches
– Bridges
– Wireless access points
– Routers
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What are the roles of clients and
servers on a network?
• A network server is a computer that provides services
to clients
• In client/server mode, there is a hierarchical structure
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What are the roles of clients and
servers on a network?
• A peer-to-peer network requires no server; treats every
computer equally
– Workstations can store network data and transport it
directly to others without central server
– Peer-to-peer technology forms the basis for file-sharing
networks
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How does the Internet work?
• The Internet is a global communications network
sometimes called “network of networks”
– Uses the TCP/IP protocol
– Collection of networks tied together by high-speed
links called Internet backbone
• The Internet backbone is maintained by network
service providers (NSPs)
– Tied together by network access points (NAPs)
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How does the Internet work?
• ISP (internet service provider) is a company that offers
access to Internet
– ISP connects to NSP to access the Internet backbone
• Every device on the Internet has a unique IP address to
identify it
– IPv4 vs. IPv6
– Static IP address vs. dynamic IP address
• DHCP automatically assigns IP addresses
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How does the Internet work?
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How does the Internet work?
• Many servers also have a domain name, which is easier
to remember
• A domain name ends with an extension (top-level
domain)
– nike.com
• ICANN is the global organization that coordinates
technical management of the Internet’s Domain Name
System
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How does the Internet work?
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How do I connect my computer to the
Internet?
• Computers can connect to the Internet through
– Telephone lines
– Cable television systems
– Cellular networks
– Wireless hotspots
– Local area networks
• The capacity of an Internet connection is sometimes
referred to as bandwidth
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How do I connect my computer to the
Internet?
• Fast connections are referred to as broadband
– 6 Mbps or more
• Symmetrical connections transfer data upstream and
downstream at the same rate
• Asymmetrical connections transfer data downstream
faster than upstream
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How do I connect my computer to the
Internet?
• Always-on connections remain active even when you
are not online
• Types of Internet service
– Cable Internet service
– DSL
– Dial-up Internet service
• Voiceband modem
– Satellite Internet service
– Wi-Fi hotspots
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How do I connect my computer to the
Internet?
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What are the advantages of networks?
• Advantages of using networks include:
– Sharing networked hardware can reduce costs
– Sharing networked software can also reduce costs
– Networks can provide access to a wide range of services
of specialized peripheral devices
– Sharing data on a network is easy
– In business environments, networks provide a means to
monitor and control many aspects of an enterprise
– Networks are convenient
– Networks enable people to work together
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How do networks facilitate
communication and collaboration?
• Communication and collaboration tools have their own
unique uses:
– Message boards, online bulletin boards, and
newsgroups
– File Transfer Protocol
– Voice over IP
– Instant messaging
– Text messaging
– Web conferencing
– Chat rooms
– Social networking
– Blog
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How do I choose the right
communications tools?
• When selecting one or more tools for a task, keep in
mind the following factors:
– Media
– Audience
• RSS
– Confidentiality
– Community
– Convenience
– Overhead
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Do networks have disadvantages?
• The primary disadvantage of networks is their
vulnerability to unauthorized access
• Network administrators create network policies,
supervise network maintenance, and implement security
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Do networks have disadvantages?
• Fundamental network security principles include the
following:
– Grant access only to authorized users
– Use authentication procedures
– Install protective technology
– Monitor the network for unusual traffic
• Wireless networks are much more susceptible than
wired networks
• Loss of autonomy
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Do networks have disadvantages?
• Home networks face many of the same threats as larger
networks
• Network security includes the following steps:
– Make sure that all network computers require user IDs and
passwords
– Install antivirus software on all computers and keep it
updated
– Activate the firewall software provided by your operating
system
– Activate encryption on wireless networks
– Install operating system updates as they become available
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Do networks have disadvantages?
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