Twisted copper wire,used for standard telephone lines and
Solid copper core,more than 80 times the capacity of twisted
Light carries data ,more than 26,000 times the capacity of
Radio waves connect wireless devices including cell phones
and computer components.
High-frequency radio waves ,travels in straight line through
Microwave relay station in the sky ,used by GPS devices.
Infared light travels in a straight line.
-Modulation: Process of converting
digital to analog and demodulation
is vice versa.
-Enable digital microcomputers to
communicate across different
media,including telephone wires,
cable lines, and radio waves.
-For years, individuals relied on dial-up
services using existing telephones and
telephone modems to connect to
internet. This type of service has been
replaced by higher-speed connection
services including DSL,cable,satellite,
and cellular services.
-DSL(digital subscriber line)
-Digital subscriber line(DSL) service
-Satellite connection service
Description types of modems
-Used to connect a computer directly to a telephone line.
-internal : system board –external : system unit
DSL(digital subscriber line) modem
-Uses standard phone lines to create a high- speed connection directly to
phone company’s offices.(usually external-connect to system unit using
USB or Ethernet ports.
-Uses the same coaxial cable television.
-creates high- speed connections like DSL using system unit’s USB or Ethernet
-Known as WWAN(wireless wide area network).
- Usually plug-in USB or ExpressCard device that provides very portable highspeed connectivity.
Description of Connection Service
Digital subscriber line(DSL) service
-Provided by telephone companies using existing telephone lines to provide
Example:ADSL(asymmetric digital subscriber line)-faster than dial-up
-Provided by cable television companies using their existing television cablesfaster than DSL
Satellite connection services
-Use satellite to provide wireless connections-slower than DSL and cable
modems-but are available almost anywhere using satellite-receiving disk.
-3G or 4G to provide wireless connectivity to the internet-not fast as the
other services but are rapidly growing in popularity for mobile
devices(phones and other portable devices.
Measurement of the width or capacity of the communication channel.
A set of communication rules for the exchange of
A communication system that connects two or more computers so
that they can exchange information and share resources.
Device that is connected to a network. It could be a computer,
printer, or data storage device
A node that requests and uses resources available from other
nodes. Typically, a client is a user’s microcomputer.
A node that shares resources with other nodes.
A specialized server that manages resources ,such as user
accounts, for an entire network.
Any computers system that can be accessed over a network.
Central node that coordinates the flow of data by sending
messages directly between sender and receiver nodes.
Expansion cards located within the system unit that connect the
computer to a network -LAN adapter
(NOS) Network Control and coordinate the activities of all computers and other
operating system devices on network.
A computer specialist responsible for efficient network operations
and implementation of new networks.
Describe how network is arranged and
how resources are coordinated and
Describe the physical arrangement of the network.
• Star network -each device is connected directly to a
central network switch.
•Tree/hierarchical network –each device is connected
to a central node, either directly through one or more other
• Mesh network -each device connected to more than one
Define how information and resources are shared
Clients request services; server provide services and
coordination; efficient network management software;
All nodes act as clients and servers ;easy and inexpensive;
lacks security controls.
-private network within an
organization that resembles the
-use browsers, Web sites, and Web
-private network that connects
more than one organization.
-to allow suppliers and others
limited accesses to their networks.
-to increase efficiency and reduce
-consists of hardware and software that
control access to a company’s intranet
and other internal networks.
Intrusion detection system (IDS)
-work with firewalls to protect an
Virtual private networks(VPN)
-create secure private connection
between a remote user and an
organization’s internal network.
Careers in IT
-manage company’s LAN and WAN networks.
-responsible for design, implementation, and maintenance of
-Responsibilities include maintenance of both hardware and software
related to a company’s intranet and Internet networks.