NETWORK TERMS
1. List and briefly describe the role of the three components used in any communication system.
The three components used in any communication system are the transmitter, the medium (something to carry the message) and a receiver.
2. What is a network?
A network is a collection of computers and related devices such as printers and modems that are connected to each other by some type of medium such as cables. The connections between the devices allow them to communicate with each other and to share programs and data.
3. Name four basic services provided by a network.
The four basic services provided by a network involve sharing. Computers connected to a network can communicate (share messages) with each other and they can share hardware, programs, and data.
4. What do the letters LAN stand for? List five different hardware components that you might find connected to a LAN.
the letters LAN stand for Local Area Network. Five hardware components you might find attached to a LAN are workstations (typically personal computers), a file server, network interface cards (NIC), cables and printers.
5. Define the term protocol. Include in your answer two different types of protocols we discussed in class.
Protocols are a set of rules that governs communications. For example, when a modem sends a message to another modem, the receiving modem must have some way to determine that the message it received is the same as the message that was sent. Connected modems use a variety of communication protocols to accomplish this. Two protocols in use today are http, hypertext transport protocol and ftp, file transfer protocol.
6. What do the letters WAN stand for? List two ways a WAN differs from a LAN.
The letters WAN stand for wide area network. One major difference between the two types of networks is the geographical area they serve. A LAN's service area is usually confined to a room or one floor in a building while a WAN covers a much larger area such as a city or a state, or, in the case of the Internet, the entire planet. Another difference between the two is the equipment that forms the network. A LAN is composed of computers, printers and other types of equipment that would be commonly found in any computer store. The components of a WAN are much more sophisticated and expensive and might include mainframe and mini computers, satellites, routers and fiber optic cables.
7. Define the term client/server computing.
The term client/server computing refers to a type of network where a group of individual terminals, the clients, share a connection to a central computer called a server. The server provides processing power and storage to the clients.
8. How does a dumb terminal differ from an intelligent terminal?
There are two types of terminals you might find connected to a server, dumb and intelligent. A dumb terminal combines a keyboard and a monitor with a connection to a server. A dumb terminal can display data received from a server but cannot change it in any way. An intelligent terminal combines a keyboard and a monitor with a CPU, RAM and usually storage too. Once connected to a server, an intelligent terminal receives data from the server and can process and store that data independently of the server.
9. What is the role of a computer used as a file server?
A file server is the central computer on a file server type LAN. It is dedicated to the role of running the network. Some space on its large hard drive is made available to hold programs and data files that can be accessed by the workstations connected to the network. The file server also contains most of the network operating system.
An important measure of a network's performance is response time. Response time is the amount of time that elapses between a request for some type of service such as opening a file and when the service is actually provided. In large LANs, the number of requests for service made on the file server can slow down response time. In order to reduce the number requests the file server must handle, other types of servers (computers) are often connected to the network. One such type of server is a print server. A print server is a computer attached to a network. A print server has one function, to handle all print requests. Whenever a user prints a file, the print request is passed along to the print server thus freeing the file server to handle other requests. Often there will be many files sent to the print server for printing at the same time. The print server receives these requests and lines them up (places them in a queue) in the order they were received.
10. What are the two types of LANs we discussed? Briefly describe the differences between the two types of LANs.
The letters LAN stand for local area network. There are two types of LANs, file server and peer to peer. The two types of LANs are distinguished by the presence of lack of a central computer called a file server. A file server LAN has a central computer that is used exclusively to provide for the needs of the network. This type of LAN gets its name from this computer. The file server is a central computer that is distinguished from other computers attached to the network by its large hard drive and large amount of RAM. The file server also contains the network operating system, the software program that in a sense creates the network. The file server is not used by anyone for typical applications such as word processing or email. Instead, it is used to provide storage and programs for the workstations connected to it.
By contrast, a peer to peer LAN does not have a central computer. All computers connected in a peer to peer LAN are used by one or more users as their personal computer. Because the computers are connected to each other, the individual users can still share hardware, programs and data.
There are advantages and disadvantages to either type of LAN. A file server LAN allows greater control of the network. With a file server LAN, often there is one person called the network administrator who is responsible for seeing that the network is always running. The net administrator also controls access to the network and other functions such as maintaining network security and seeing that regular backup are performed. Although the file server and administrator means added expense, having a central computer and one person responsible for network make it more likely that tasks such as maintaining network security and back up will be done.
Peer to peer networks are less expensive to create and maintain. For example, there is no need to dedicate one computer as a file server. But because there is no central control, key functions such network security and backup are left to individual users and often go undone. If security is not maintained or back up isn't performed regularly, the entire network and its continued operation may be compromised.
11. Define the term topology. Include three different types of LAN topologies in your answer.
The term topology refers to layout of the devices attached to a LAN and how the devices are connected to each other. Three different network topologies are bus, star and ring.
12. Name three types of cabling used to transmit information over a network.
Three types of cables used to carry signals over a network are twisted pair, coaxial and fiber optics. Twisted pair and coaxial are both copper cables that carry electricity; fiber optic cable is composed of strands of glass that carry light. Twisted pair cabling is similar to the wire used to connect a telephone to a wall jack while coaxial cabling is similar to the cable used to connect a TV or VCR to a cable company's signal. Twisted pair is the cheapest and easiest to install but also carries the smallest amount of information at a time. Twisted pair is a common choice for small, peer to peer networks found in small offices or homes. Coaxial cable, while more expensive than twisted pair, also carries more information and is commonly used for file server networks. Fiber optic cabling is not used for LANs; it is too expensive. Fiber optics is used in WANs where large amount of data are transmitted over long distances. Because fiber optic cables carry light instead of electricity, the signal they carry is less susceptible to noise and other types of signal degradation.
13. List three differences between transmitting information over coaxial cable versus using fiber optic cable.
Coaxial cable consists of copper wire; fiber optic cables consist of strands of glass. Coaxial cable transmits electricity while fiber optic cables transmit electricity. Coaxial cable transmits much less information at one time than fiber optic cabling.
14. Define the term wireless communication. List two methods for transmitting data wirelessly.
Wireless communications is communications that take place without the use of cables. Two types of wireless communication used by LANs are infrared and radio frequency (rf).
15. What is the role of a network operating system? Include two examples of network operating systems in your answer.
A network operating system plays a similar role for a network to the role an operating system plays for an individual computer. The network operating system controls the flow of information from one component of a network to another component. Whether it is a request to print a file or start a program stored on the file server, it is the network operating system that receives the request and sees that it is carried out properly. The network operating system is found in two places, on the file server and the individual workstations. Most of the network operating system is installed on the file server. Individual workstations only contain as much of the network operating system as they need to make communicating with the network possible.
Examples of file server type operating systems are Netware from the company called Novell and Windows NT from Microsoft. The Macintosh operating system and Windows 95 serve as both personal computer operating systems and as peer to peer network operating systems.
16. Define the term login.
Logging in is the process of identifying yourself to the network for the purpose of gaining access to the services provided by the network. Logging in usually involves entering a username and a password.
17. What is a password? What are some precautions you should take to protect your password?
A password is a string of characters known only to the individual user. The purpose of a password is to identify a user at login time and to verify their identity.
Some precautions you can take to protect your password are:

• Make it at least five characters long.
• Never tell anyone your password.
• Avoid writing it down but if you do write it down, don't keep it near your computer.
• Don't use common information about yourself such as your last name or your birth date or the name of your dog. If you must use personal information, insert random characters such as numbers or punctuation marks in the information you choose.
• Don't use words from the dictionary.
• Change your password regularly and don't use the same password for more than one account.

18. What role does a modem play in the transmission of data?
Computers store information in a digital format. Most telephone lines carry analog signals. In order to transmit digital information over analog telephone lines, the digital information must be converted into an analog format. The role of a modem is to perform this translation. The term modem is composed of parts of two words, mo from modulate and dem from demodulate, mo dem. At the transmitting end of the communication link, a modem modulates or changes digital information into a form that can be sent over phone lines. At the receiving end, the other modem demodulates the incoming signal or changes it from an analog signal back into a digital format.
19. How is the speed of a modem measured?
The speed of a modem is measured in bits per second (bps). Today's fastest modems can theoretically transmit data at 53,300 bps although telephone line conditions can significantly reduce the actual transmission speed. To obtain a more meaningful measure of a modem's speed, divide its bps rating by 10. The result is the number of character per second the modem can transmit.
20. Define the terms uploading and downloading.
The term uploading means sending data from your computer to another computer that you are connected to, typically by modem.
Downloading is the reverse of uploading. When you download, you are receiving data from another computer and storing it on your computer.
21. Define the terms simplex, half duplex and full duplex.
Simplex communication involves a one way transfer of information. The transmitter sends a message but there is no way for the receiver to send a message back to the transmitter using the same medium.
Half duplex communications involve two way transfer of information but only in one direction at a time. The transmitter sends while the receiver accepts the message. The two components can change roles so that the receiver becomes the transmitter.
With full duplex communications, information can flow in both directions at the same time.
22. Give an example of simplex, half duplex and full duplex communications.

• Simplex: radio or TV.
• Half duplex: CB radio or fax.
• Full duplex: telephone or email

23. What do the letters ISDN stand for? List three differences between transmitting data over ISDN lines and transmitting data over normal telephone lines.
The letters ISDN stand for integrated services digital network. ISDN is an all digital phone connection. ISDN has several advantages over regular phone lines. Because ISDN is an all digital connection, there is no need for a modem. However, you still need a piece of hardware called a terminal adapter attached to your computer to send signals over the ISDN lines. ISDN lines are faster than a POTS (plain old telephone service) line. While today's fastest modems theoretically can transmit data at speeds of 53.3 Kbps (kilobits per second), in actuality their top speed is closer to 40 Kbps under ideal conditions. Under less than ideal conditions (which is usually the case), top modem transmission speeds are closer to 33.6 Kbps. By contrast, an ISDN line can transmit data at 56 Kbps. Since an ISDN line is actually two lines in one, it is often possible to combine the two lines into one to achieve transmission speeds up to 128 Kbps. Also, because an ISDN line is two lines in one, it is possible to transmit data and talk to someone at the same time. Another benefit provided by an ISDN line is that all digital connections are less susceptible to corruption of the transmitted data.
24. What is a T1 line? How does T1 differ from T3?
T1 and T3 refer to high speed digital services offered by communications companies. The difference between T1 and T3 lines is the amount of data they can carry in a given amount of time.

• T1 can carry up to 1.544 Mbps
• T3 can carry up to 44.736 Mbps or approximately 28 times as much data as a T1 line.

25. What do the letters DSL stand for? How does DSL differ from cable?
DSL and cable are examples of high speed (broadband) communications available for small businesses and personal use at much more affordable prices than T1 or T3.
The letters DSL stand for digital subscriber line. DSL is a telephone connection that can transmit data over existing phone lines up to 50 times faster than today's fastest modems. Although cable can be even faster than DSL, because it is a type of party line, as more people in a local cable cluster use their connection, the slower everyone's service becomes. Cable and DSL are not available in all areas of the country. The farther you get from a large city, the less likely your chances of getting either type of service. Both types of connection are priced competitively.