Chapter 1 - Introduction to Computer Networks and Data Communications

Question 1

Computer network

Answer 1

An interconnection of computers and computing equipment using either wires or radio waves over small or large geographic areas

Question 2

Local Area Network

Answer 2

networks that are small in geographic size spanning a room, floor, building, or campus

Question 3

Metropolitan area netowork

Answer 3

networks that serve an area of 1 to 30 miles, approximately the size of a typical city

Question 4

Wide area network

Answer 4

a large network that encompasses parts of states, multiple states, countries, and similar devices

Question 5

Personal area network

Answer 5

a network of a few meters, between wireless devices such as PDAs, laptops, and similar devices

Question 6

Voice network

Answer 6

a network that transmits only telephone signals (almost extinct)

Question 7

Data network

Answer 7

a network that transmits voice and computer data (replacing voice networks)

Question 8

Data communications

Answer 8

the transfer of digital or analog data using digital or analog signals

Question 9

Telecommunications

Answer 9

the study of telephones and the systems that transmit telephone signals (becoming simply data communications)

Question 10

Network management

Answer 10

the design, installation, and support of a network, including its hardware and software

Question 11

Network cloud

Answer 11

a network (local or remote) that contains software, applications, and/or data

Question 12

Advantages of networking

Answer 12

• Provide a means to share software, data, equipment and communications quickly, easily and inexpensively.

• Saves time and money
-Provides quick access to files and resources

• Provides a means to secure data.
-Protects information from being stolen or destroyed

Question 13

Disadvantages of networking

Answer 13

• Additional personnel are often needed to maintain and modify the network
• Losing access to files when the network is down
• Vulnerability to hackers, viruses and dissatisfied workers.

Question 14

Microcomputer-to-Local Area Network Layout

Answer 14

• This network Highly common throughout business and academic environments, and homes
• Medium-to high-speed connection
• Computers(devices) requires a NIC (network interface card) connects to a hub-like device(switch)

Question 15

Microcomputer-to-Internet Layout

Answer 15

• Popular with home users and small businesses
• For some, a dial-up modem is used to connect user’s microcomputer to an Internet service provider
• Technologies such as DSL and cable modems are replacing modems

Question 16

Local Area Network-to-Local Area Network Layout

Answer 16

• Found in systems that hava two or more LANs and a need for them to intercommunicate
• A bridge-like device(such as a switch) is typically used to interconnect LANs

Question 17

Local Area Network-to-Wide Area Network Layout

Answer 17

• One of the most common ways to interconnect a user on a LAN workstation to the Internet (a wide area network)
• A router is the typical device that performs LAN to WAN connections
• Routers are more complex devices than switches

Question 18

Local Area Network-to-Metropolitan Area Network Layout

Answer 18

• Used to interconnect companies (usually their local area networks) to networks that encompass a city
• High-speed networks with redundant circuits
• Metro Ethernet is latest form of metropolitan LAN

Question 19

Cell Phone Layout

Answer 19

• Constant expanding market across the U.S. and world
• Third generation services available in many areas and under many types of plans with fourth generation services starting to appear
• Latest generation includes higher speed data transfers (100s to 1000s of kilobits per second)

Question 20

What is the two most common architectures known today?

Answer 20

OSI (Open Systems Interconnection) and TCP/IP Protocol

Question 21

The layers of TCP/IP

Answer 21

• Application layer
• Transport layer
• Internet layer
• Network interface layer (Physical)

Question 22

Application layer

Answer 22

• The application layer works with specific networking application.
• Common network application include web browsing, e-mail, file transfers and remote logins

Question 23

Transport layer

Answer 23

• To ensure reliable data by sequencing packets and reassembling them into their correct order.
-Packets are transmitted over many miles and may use different routes. The packets may not arrive in the same sequence they were transmitted and may require reassembly into their correct order. Reassembly into the correct order is especially important in transmitting digital images.

Question 24

Internet layer

Answer 24

• Sending packets across potentially multiple networks. Internet-working requires data from the source network to the destination network. This process is called routing.

Question 25

In the internet protocol suite, the Internet Protocol performs two basic functions:

Answer 25

Host addressing and identification

Question 26

Packet routing

Answer 26

This is the basic task of sending packets of data (data-gram) from source to destination by forwarding them to the next network router closer to the final destination.

Question 27

The Open System Interconnection (OSI) Model

Answer 27

• Application layer
• Presentation layer
• Session layer
• Transport layer
• Network layer
• Data-link layer
• Physical layer

Question 28

Presentation layer

Answer 28

• Responsible for “final presentation” of data (code conservation, compression, encryption). It is responsible for converting character codes into a code that is recognizable by a computer.

Question 29

Session layer

Answer 29

• The session layer establishes a connection between two different computers and provides security based on computer and user name recognition. The two computers may not normally by compatible for data exchange, such as PC and a Macintosh. The session layer and transport layers are sometimes combined. When you think of the session layer, think of a handshake at the introduction and at the end of the meeting.

Question 30

Network interface layer (Physical)

Answer 30

• Network Access Layer is the first layer of the four layer TCP/IP model.

• Network Access layer defines details of how data is physically sent through the network, including how bits are electrically or optically signaled by hardware devices that interface directly with a network medium.
-Coaxial cable, optical fiber, or twisted pair copper wire.

As packets are transmitted from one network to another, several different routes may be used.

Question 31

Network layer

Answer 31

• First layer of the TCP/IP model
• Defines details:
-How data is physically sent through the network
-How bits (0,1) are electrically or optically signaled by hardware devices
• Interface directly with a network medium:
-Coaxial cable
-Optical fiber
-Twisted pair copper wire
• Several different routes may be used

Question 32

Data link layer

Answer 32

• The data link layer describes how the raw data is packed for transfer from one network interface card to another. The data link layer also contains information such as the address of the source and destination and the size of the packet, and it provides for error checking.

Question 33

Physical layer

Answer 33

• Is the lowest layer of the model. It consists of the cable and connectors used for constructing the network. This layer is only concerned with how digital signals, the binary 1s and 0s, are carried electrically from one networked device to another.
• Handles the transmission of bits over a communications channel
• Includes voltage levels, connectors, media choice, modulation techniques

Question 34

Data transmission

Answer 34

The movement of information using some standard methods:
• Electrical signals
	-A conductor
• Optical signals:
	-Optical fibers
	-Electromagnetic areas

Question 35

Types of Network Subnets

Answer 35

• Circuit Switched Network

* Packet Switched Network

Question 36

Circuit Switched Network

Answer 36

• A dedicated circuit is established between:
-Sender
-Receiver
~All data passes over this circuit

• Example:
-Telephone system

• Network must establish a connection before the sender and the receiver

• Connection is dedicated until:
-One party or another
~Terminates the connection

Question 37

Packet Switched Network

Answer 37

• All data messages are transmitted using:
-Fixed-sized packages
~Called packets

• More efficient use of telecommunications

• Datagram:
-Each packet:
~On its own
~May follow its own path

• The source breaks long messages
-Into smaller chunks of data
~Known as packets

Question 38

Network based transmission technology

Answer 38

• Broadcast Network

* Point-to-Point Networks

Question 39

Broadcast Network

Answer 39

• Have a single communication channel
-Shared
~By all machines on the network
• Allow the possibility of:
-Addressing a packet to all destinations
~By using a special code in the address field
• Called broadcasting
• Some broadcast systems:
-Support transmission to a subset of the machines
~Known as multicasting

Question 40

Point-to-Point Networks

Answer 40

• Consists of many connections between:
	-Individual pairs of machines
• First visit:
	-One or more intermediate machines
• Routing algorithms:
	-Plays an important role
• General rule:
	-Smaller, geographically localized networks
		~Use broadcasting
	-Larger networks
		~Use point-to-point