Complete Network Course

COMPUTER NETWORK COURSE Table of Contents:

COMPUTER NETWORK COURSE..............................................................................................1 Table of Contents:...............................................................................................................1

DON’T FORGET – Get your free 30 day trial version of our Remotescope Network Management Software – TO DOWNLOAD CLICK HERE ..............................................................................................................................1 INTRODUCTION.....................................................................................................................................................2 TYPES OF NETWORKS.........................................................................................................................................2 Ethernet.....................................................................................................................................................................2 NETWORK CONNECTIONS .................................................................................................................................2 Bus Network..............................................................................................................................................................3 PROTOCOLS ...........................................................................................................................................................5 TCP/IP ......................................................................................................................................................................5 IP Addresses..............................................................................................................................................................5 Static or Dynamic?....................................................................................................................................................5 Computer Names.......................................................................................................................................................5 SECURITY ..............................................................................................................................................................6 Encryption.................................................................................................................................................................6 VIRUS SOFTWARE ................................................................................................................................................6 ACCESS CONTROL ...............................................................................................................................................6 FIREWALLS ............................................................................................................................................................6 Conclusion.................................................................................................................................................................7 Designed to help you save time in your .................................................................................7 every day quest of troubleshooting PCs..................................................................................7

GLOSSARY..............................................................................................................................................................8 DON’T FORGET – Get your free 30 day trial version of our Remotescope Network Management Software – TO DOWNLOAD CLICK HERE 

Computer Network Course - © 2004 Micro 2000 UK - www.micro2000.co.uk

1

INTRODUCTION A network is a group of things that are connected together. In a computer network, the things that are connected are computers, of course. A computer network can be as small as two computers but there is no maximum size, and many networks have hundreds or thousands of computers. There are three main reasons for connecting computers in a network:

1. Share information. This can be messages such as e-mail, or it can be files that are stored on one computer and used by someone at a different computer. A printer that can be accessed from different computer systems is a shared resource. So is an Internet connection used by more than one computer. Centralized control. In most offices, the management determines what the computers may be used for and what kind of resources and support they need. This is much easier to deal with if the computers are connected.

2. Share resources. 3.

TYPES OF NETWORKS Just as there is no limit to the number of systems in a network, there is also no limit to the geographical size of a network. As a practical matter though, there are some structural differences between a network of computers all in the same room, and a network connecting computers in Los Angeles to ones in Sydney Australia. The most common network includes computers that are close together, usually in the same building or office. This is called a Local Area Network, abbreviated LAN. The computers in a LAN are usually connected with cable made up of pairs of wires, but faster (and more expensive) cables are made from glass fibers, called fiber optic cable. A network may even use radio waves, in which case it is a wireless LAN. When the computers being connected are far apart, typically in different cities, it is called a WAN or Wide Area Network. The connection is usually done with special high-speed lines leased from the phone company, but it is also possible to connect over an ordinary phone line using a device called a modem. It’s slow, but possible. Accessing a network through a phone line and modem is called a dial-up connection. The biggest of all networks is the Internet. The backbone of the Internet consists of powerful computers all over the world with high-speed connections between them. Individual computers such as yours then connect to this backbone through an Internet Service Provider or ISP. Ethernet Most LANs in existence today use a technology called Ethernet. In an Ethernet network, every piece of information put on the network is seen by every other computer on the network, and each computer must determine if that information is meant for itself. To make this work, before the information goes out on the network it is first broken up into small pieces called packets, and each packet has added to it the address of the computer that should receive it. The part of the packet containing the address is called the header. Header

Packet diagram Then, each computer looks at the address on each packet that comes by on the network cable, and copies the ones that have the right address. The computer that sent the packet is called the source, and the one that is supposed to receive it is called the destination.

NETWORK CONNECTIONS When a packet comes out of the computer that originated it, that packet must have a complete electrical path to every other computer. The simplest way to do this is to have a cable that goes from one computer to the next until it has connected to each one. This is called a bus network.

Computer Network Course - © 2004 Micro 2000 UK - www.micro2000.co.uk

2

Bus Network A bus network is the simplest to explain and draw, but it’s not often the simplest one to use, especially if computers are distributed around various offices in a building, and then get added, taken away, moved around and so forth. A much more practical way to connect more than a couple of systems is to connect each one to a device called a hub. Each system has a cable that goes from it to the hub, and inside the hub an electrical connection is made between all of the cables. Each place where a cable plugs into the hub is called a port.

5-port hub ports To create larger networks, hubs can use one or more of their connections to connect to other hubs. This is called a star network, but as far as the electrical signals are concerned, they go from one computer to every other computer, no different than the bus network.

3-hub star network When networks get really big, with 100s of systems or more, it’s no longer such a good idea to have each computer look at every packet, because almost none of the packets will be for that computer. The large network can be broken up into smaller groups called subnets, and these are connected with a device called a data switch, or just a switch. Within each subnet, all of the computers still see every packet, and so does the switch. Normally the switch won’t pass those packets on to the other subnets, but if the packet has an address for a destination in another subnet, the switch will pass the packet to the port for that subnet. All of the systems in that subnet will then see the packet, including the system it is actually addressed to. In order to know where to send a packet, the switch must have a table of addresses for each subnet.

Computer Network Course - © 2004 Micro 2000 UK - www.micro2000.co.uk

3

Switch with 4 subnets The simplest form of a switch is called a bridge, and it connects just two subnets. A bridge only needs two ports then, one for each of the subnets. Sometimes a network will be so big and complex that one switch isn’t enough to connect all of the subnets. In that case the subnet receiving a packet might be connected to a different switch than the subnet where the packet started. This is a more complicated problem, because the switch would need to know not only the packet’s destination, but also where to send it next to make sure it got there. For this, a smarter device is needed, called a router. The router needs to know not only the subnet addresses, but also the best path, or route, to get from one to another.

Route path diagram One place where routers are used in a big way is the Internet. If you send a message on the Internet, it might go through many routers before it reaches its destination. And when you surf to a website, all of the graphics and text showing up on your screen had to go through routers to find their way from the web site to your computer. By the way, every LAN that connects to the Internet becomes a subnet of the Internet, even if it has its own internal subnets.

CLIENTS AND SERVERS In addition to the various ways networked systems can be physically connected, there are two basic ways that network activities can be arranged. In one, all of the computers have equal status. This is called peerto-peer, because a peer means someone (or something) that is the equal of another. Peer-to-peer is used mostly in very small networks of less than a dozen systems. The more common arrangement is called client-server. One system, called the server, is responsible for a particular activity or resource. The other systems are called clients, and they go through the server when they want to use the function or resource that the server is responsible for. Some of the things servers are commonly used for include network administration, e-mail, printers, file storage, and Internet access. Often several of these functions will be combined into one machine. There is no rule that says a network server and a print server can’t be the same system. Clients

Server

Computer Network Course - © 2004 Micro 2000 UK - www.micro2000.co.uk

4

print server There is also no rule that says a server must serve the entire network. It is usually convenient to have a separate network server for each subnet. There are other divisions that can occur even within a subnet. Computers that need to share the same resources can be organized into workgroups. With the Windows NT operating system, the LAN can be divided into sections called domains, and each domain needs its own server called a domain controller.

PROTOCOLS A protocol is an agreed-upon standard for how something will be done. When your mother taught you to chew with your mouth closed and keep your elbows off the table, that was a protocol for proper dining. Computer protocols are the rules for connecting with other computers and exchanging information with them. Ethernet is a protocol. Earlier we called it a technology, but it is also a set of rules for how that technology is used. If each piece of hardware and software complies with the rules, then information can be correctly transferred from one from one system to another in a LAN. There are many protocols used in networking. There are some protocols that are used together with other protocols, where each one takes care of different aspects of networking. Sometimes two protocols do the same thing in different ways, and it is necessary to choose one or the other. The important thing is that both systems trying to communicate with each other have matching protocols that they can use. TCP/IP One very important set of protocols is called TCP/IP. It is important because it is what the creators of the Internet decided would be used for that particular network, which means that any computer that wants to connect to the Internet must also use TCP/IP. TCP/IP stands for Transmission Control Protocol / Internet Protocol. TCP/IP is actually in two parts. The TCP portion covers the agreements between systems about how they will carry on their ‘conversation’, and the IP portion deals with addressing the packets and routing them. The TCP part all happens in the background and we don’t really need to concern ourselves with it under normal circumstances. However, in a network that uses TCP/IP, every system must have a unique IP address, and that is something that requires human intervention in one way or another. IP Addresses An IP address is made up of four sets of numbers separated by periods. An example is: 192.168.42.122 Each of these sets of numbers is called an octet, because they started out as 8-digit binary numbers. By changing them into 3-digit decimal numbers, the whole address is shorter and easier to remember. The highest value for any octet is 255, because the highest number you can make with eight binary digits is equal to 255 in decimal. In most networks, the first three octets are the same for all systems, and the last octet is different for every machine. If there are more than 255 computers in a network, it is usually divided into smaller subnets. Static or Dynamic? There are two ways to associate a unique IP address to a specific computer. One way is for the administrator to assign a number, which stays the same unless somebody decides to change it some day. That number is then a static IP address. The other way is to assign a group of addresses to a server, and let the server hand them out as needed to any system that wants to communicate on the network. This produces a dynamic IP address. It is sometimes important to know which method is in use on a network, because with dynamic addressing, the IP address of a machine may be different each time you try to communicate with it. Computer Names The example address 192.168.42.122 is only one digit longer than a phone number with area code, but that’s plenty long enough to give most of us a hard time. It’s much easier for people to remember a name instead of a number, and for this reason computers in a network are also given a unique name. It may be something mundane like Sales14, but at least it’s a name and not a number. This is not only easier to remember, but it solves the problem of a dynamic address that changes all the time, because the computer name doesn’t normally change. It does create another problem though, because the computers use only the addresses and not the names to keep track of each other. Fortunately there is a part Computer Network Course - © 2004 Micro 2000 UK - www.micro2000.co.uk

5

of the TCP/IP protocol called address resolution, and it matches up the names and addresses so things keep rolling smoothly along.

SECURITY The problem with connecting computers to the Internet is that they are then sharing a network with many other computers from all over the world, and the users of some of those other computers are not such nice folks. Protecting the network and the information on it is one of the most important parts of a network administrator’s job. Encryption One way to protect information is to scramble it so that it appears to be gibberish unless someone has the right ‘key’ to unscramble it. Scrambling it is called encryption, and unscrambling it is called decryption. There are many ways to encrypt information, and of course just as many keys to decrypt it. Encrypting and decrypting information slows things down a bit, so a decision must be made about when to use it. For packets going around the LAN, it depends on how likely it is that someone will gain unauthorized access to the LAN, called hacking. It also depends on how much damage would be done if that happened. If the threat is severe, encryption can be done not only on the transmitted packets but also to information stored on the disk drive. For information going over the Internet, encryption is much more important unless it’s all right for the whole world to see the information. If you send your credit card number to a vendor, you must trust that vendor to encrypt and safeguard the information.

VIRUS SOFTWARE A computer virus is a little program that makes copies of itself to send to other computers. It’s very similar in some ways to contagious germs spreading a disease from one person to the next. And like diseases, some of these computer viruses have some really nasty side effects, like wiping out important files in the operating system or filling up the hard drive with garbage data. As we will discuss a little later, there are ways to keep these virus programs from getting to your computer, but they are not foolproof. A lot of viruses come in attached to e-mail, and then they will mail copies of themselves to everyone in your e-mail address folder. You can’t completely block them without blocking email, and most of us like to get e-mail from our friends and coworkers. The most important prevention for viruses is to have a good anti-virus program installed on your computer. Norton, McCaffey and Panda are probably the most popular. The next most important thing is to keep the anti-virus software up-to-date, because the delinquents who write virus software are always coming up with new tricks, and the anti-virus companies are just as quickly coming up with new versions to stop them.

ACCESS CONTROL If you have ever had a computer that was connected to a local area network, you almost certainly had to type in a user name and password to get network access. It’s two forms of ID, just like when you cash a check at department store. The network administrator used that identification information to determine what you could and couldn’t do on the network. And there may have been additional passwords to access the company’ customer database, employee payroll records, or files stored on someone else’s computer. Here are a few tips about passwords: 1. First, if you share files on your computer, use password protection for them even if they are available to everyone in the network. That way they can’t be tampered with if a hacker breaks in. 2. In choosing a password, never use your name, your birthday or other obvious personal information. The best is a random combination of letters and numbers. 3. Commit the password to memory, and if you must write it down, hide it. A password written on a post-it note stuck to your monitor is probably worse than no password at all. 4. Don’t give your password to someone you don’t know personally just because they claim to be tech support, the phone company, the police or your long-lost Aunt Matilda. Refer them to the network administrator, or better yet, get their phone number and have the network administrator call them back.

FIREWALLS In a building, a firewall is a wall to keep fire from spreading from one area to another. In a computer network, a firewall is a boundary that can block unwanted data packets. The firewall may be program running on the server or router, or it may be a separate piece of hardware or even a complete computer Computer Network Course - © 2004 Micro 2000 UK - www.micro2000.co.uk

6

system just for that purpose. In any case, its purpose is to look at all of the packets coming through, and decide which ones can pass and which ones get blocked. Ports – Several pages ago, we defined a port as the place in a hub that a cable plugs into. There is another completely different kind of thing called a port, and that is a location in a computer’s memory that is used by a device or application to send and receive data. Each application will have one (or more) of these locations for its own use. For instance, there is a common e-mail program that has port # 110, which means that the program exchanges information with the rest of the system at memory location 110. The popular game called Doom uses port # 666. When a packet is sent over a network, it will contain not only the destination address, but also the port number of the application that will use it at that destination. One of the ways a firewall controls the packets is by looking at the port number, and only passing packets with ports that are appropriate for the destination. If nobody should be playing Doom on the network’s computers, then it would make sense to block port 666. Another way a firewall can control traffic is to look at the source of the packet. It can have a ‘prohibited’ list that keeps out packets from certain IP addresses, or it can have an ‘allowed’ list and block everyone who isn’t on it. Ports can be done the same way, with a ‘prohibited’ or ‘allowed’ list of ports.

NOW – TEST YOUR KNOWLEDGE!!! Take our online Computer Network Test  CLICK HERE

Conclusion There is much more to know about security and about networks in general, if one is to be involved in managing them. The purpose of this paper is to present just enough information to enable you talk with network administrators and to understand their concerns when presenting network products to them. For additional training in this subject, we recommend the Micro2000 A+ Course. For more information on this please go to:

http://www.micro2000.co.uk/products/aplus/aplus.html

END WHY DON’T YOU DO OUR HARDWARE COURSE NOW? This is a very short course about computers. It won't make you into a computer technician, but it will let you talk to one without thinking they are speaking a foreign language. CLICK HERE

Be sure and sign up for our FREE Tech Tips too! Designed to help you save time in your every day quest of troubleshooting PCs. Subscribe to the Tech Tip Mailing List:

FREE TECH TIPS:  CLICK HERE DON’T FORGET – Get your free 30 day trial version of our Remotescope Network Management Software TO DOWNLOAD CLICK HERE  * You have permission to reprint what you just read, or any of our other articles. Use it in your ezine, on your website or in your newsletter. The only requirement is including the following footer with it; * Article by Micro 2000 Inc. Visit our Tech Tips Database Website for more original content like this. Reprinting this article is permitted with this footer included.

Computer Network Course - © 2004 Micro 2000 UK - www.micro2000.co.uk

7

GLOSSARY 802.11: The IEEE standard for wireless networking. Access point: The transceiver where a wireless node connects to the network. Also the control system in a HyperLAN network Activation: The process of validating the Console and Client seat license information. Administrator: The person in charge of managing a system or network. Advanced Encryption Standard: A 128-bit encryption used by some government agencies - Abbreviated AES Compare to DES, Data Encryption Standard. Alphanumeric: Consisting of letters and numbers. Names used in NT and RemoteScope must be made of alphanumeric characters, with no spaces, symbols or punctuation except the dash and underscore. Anti-virus software: A utility to detect the intrusion of virus programs and limit their damage. Application: A computer program to perform a specific task for the user, as opposed to the operating system that runs the computer itself. Architecture: The way something is built. Network architecture refers to the various ways a network can be put together or implemented. ASCII: American Standard Code for Information Interchange: A digital code for transmitting characters. The format used by personal computers for data exchange. Back Office: See Microsoft Back Office. Bandwidth: The carrying capacity of a data channel, usually expressed in bps (bits per second). Also called throughput or transfer rate Bit: The smallest unit of information in a computer, either a zero or a one. Boot ROM: A ROM chip added to a network card that allows a system with no local disk drive to access and boot from an operating system residing on the server. Bootleg: Something made or used illegally or without authorization. In software it refers to additional copies installed on computers other than the one for which the software was licensed. Bottleneck: A portion of a system or network that is slower than the rest of the data path, either because of its throughput speed or because of multiple data streams converging at that point. Bps: Abbreviation for bits per second. Bps: Abbreviation for bytes per second. Bridge: a device for passing signals between two LANs or two segments of a LAN. Broadcasting: Sending a message simultaneously to all systems of a network, without requiring an acknowledgement. Compare to multi-casting. Brouter: A device combining the capabilities of a bridge and a router. Browser: A program that allows viewing of HTML pages. Byte: A unit of digital data consisting of eight bits. CAT 5: The twisted-pair cable normally used for networks Cisco: A large supplier of networking hardware and software, including router and security products. Client: 1. A workstation in a client-server network. 2. A system controlled by the Remote-Scope Console. Client-server network: An arrangement where some programs, files or other resources are located on one computer, called the server, but are available to other systems on the network, called clients. Command line: In a text-based operating system, the line on which the user types instructions for the system. Compression: A method of compacting data for storage or transfer. Configuration: The way the parts of a system or network are arranged or connected. Console: The primary RemoteScope program from which Clients are controlled. Also, the workstation on which it is installed Data Encryption Standard: A common 56-bit encryption standard, and the one used by RemoteScope. Abbreviated DES Computer Network Course - © 2004 Micro 2000 UK - www.micro2000.co.uk

8

Data switch: A device used to connect multiple networks or segments. It differs from a hub in that packets are routed to the proper port rather than being broadcast on all ports. Dial-up connection: Accessing a network or the internet through a modem attached to a standard phone line. Direct connection: The local connection to a network made by a network card, as opposed to the remote connection made by a modem. Distribution: Copying a file or software package to multiple Client systems. DNS: Domain Name System. Domain: An area under a single point of control. On the Internet there are different levels of control and each is a domain. At the lowest level is each local area network that has its own network ID. Top-level domains are .com, .org etc. In some operating systems such as NT, a domain is a group of associated computers within a LAN. Domain Name System (also Domain Name Service): An Internet service that translates the domain names used by people into the numeric IP addresses used for routing on the Internet. The domain name system is actually a network of domain name (DNS) servers. Download: Copy a file from another computer to one's own, over a network or from the Internet. Driver: A file containing information the operating system needs to interact with a hardware device or software module. In the case of hardware, it is usually called a device driver. Dynamic addressing: Assigning IP addresses as needed from a pool of available addresses maintained on a server, rather than assigning a fixed IP address to each system. Encryption: Encoding data to protect it from being intercepted by unauthorized persons. RemoteScope encrypts all data transmissions, all password and user name information, and some application files. Ethernet: A widespread standard for local area networks. There are versions for coaxial cable, twisted pair cable, fiber optic cable and wireless. Exporting: Outputting report information in another format, to be used in a different application - RemoteScope provides nearly 40 formats and variations for exporting report information. Firewall: A barrier in a network that will only pass packets authorized to reach the other side. Frame: A data structure used in network transmissions, consisting of one or more headers and a footer bracketing a data packet. Full control: One of the three remote control modes. Only the user of the Console will be able to enter keystrokes and mouse movements for the Client machine. The user at the Client has no keyboard or mouse control. Group: A collection of RemoteScope Clients assembled into a unit for common access. Actions can be taken with all clients in a group simultaneously instead of one at a time. Header: Data that comes in front of a data packet, containing address and handling information for that packet. HTML: HyperText Markup Language. A program language for writing web pages that can include links to other pages. HTTP: HyperText Transfer Protocol. The standard for accessing HTML pages Hub: A device providing a central point of connection for network cables. I/O port: A hex memory address used by a device or program to exchange data with the rest of the computer system. IEEE 802.11: A common standard for wireless networking, issued by the IEEE. Internet: A cooperative system linking computer networks worldwide. Inventory: A list of the installed hardware, applications and operating system for a particular system, maintained in a database at the Console. Internet Protocol: The portion of the TCP/IP suite that specifies packet formatting, naming and routing. Abbreviated IP IP address: A 32-bit number designating an individual machine on a network or on the Internet. It is usually listed as four groups of three-digit decimal numbers. IPv6: A plan for expansion of the domain name system. It stands for Internet Protocol version 6. IRQ: Interrupt ReQuest. The signal that a peripheral or program uses to request service from the CPU. There are 15 different IRQ values that can be used by system hardware. ISP: Internet Service Provider. An organization providing access to the Internet ISS file: A file created for a silent or unattended install using InstallShield. It contains a record of all the keystrokes required to complete the installation. ISS stands for InstallShield Silent Response. LAN: Local Area Network. A group of computers connected to each other by cable or some form of wireless technology, and usually located within the same building. Computer Network Course - © 2004 Micro 2000 UK - www.micro2000.co.uk

9

Log on: Gain access as a current user of a system or network, usually by entering a user ID and password. Mbps: Megabits per second. A data transfer rate of one million bits each second. Messaging: A form of network communication that appears instantly on the monitor of the receiving system - Also called instant messaging Microsoft Back Office: A collective term for server functions other than domain controller, such as file and print server, on a Microsoft network. Modem: A device for sending computer data over a voice phone line. Modem stands for modulate/demodulate. Multi-casting: Sending a message simultaneously to a select group of systems. Compare to broadcasting. Name resolution: The process of converting a people-friendly alphanumeric system name or domain name into the IP address recognized by the network NetWare: A network server operating system from Novell. Network: A system or group of interconnected elements. A computer network is a group of computers and peripherals connected together to communicate with each other and to share information and resources. Network adapter card: A plug-in expansion card with a connection for a network cable, or an antenna for wireless transmission. Also called a network interface card or NIC NIC: Network Interface Card. A plug-in expansion card with a connection for a network cable, or an antenna for wireless transmission - Also called a network adapter card Node: Any point in a network that can influence the flow of data on that network. This usually refers to each of the systems and peripherals on the network that have their own physical device address. Novell: A software company that produces NetWare and other networking products. NT: Windows NT, an operating system from Microsoft. Offline: Not available to the network. Online: Turned on and connected to the network. Operating system: The master control program that runs the computer and allows it to execute applications. OS X: The latest operating system for Macintosh computers, based on the Linux kernel but with a more user-friendly graphic interface. It includes networking capabilities. Packet: A block of information configured for transmission over a network. Password: A string of characters that a user must enter to gain access to a resource that is password-protected. PC Anywhere: A common program used for control of a remote system. Peer-to-peer: A small network where each computer has equal status and control. Compare to client-server. Port: An address in memory used to transfer data into and out of a system. TCP/IP needs a port number to be able to provide the communication connection. RemoteScope allows configuring the Port number between 10000~50000. Protocol: An agreed-upon standard for how something will be done. Computer protocols are rules for the exchange of information. Proxy server: A server that sits between a client and a web server and represents itself to each end as being the other. It can be used in two ways. For the web server it can cache frequently accessed pages to reduce the web-server's traffic. For security of the LAN clients it can present a single IP address to the Internet and prevent direct access to the rest of the LAN. Remote Access Service : The protocol used in Windows NT and its successors to provide remote dial-in access to a network running Windows NT or its successors. Abbreviated RAS Remote connection: The link between a modem and a network through a dial-up connection. Compare to the direct connection made by a network card. Repeater: A device to boost network signals transmitted over a long span. RJ-11: A four-wire jack used with Cat3 cable for telephone RJ-45: An eight-wire jack used with Cat5 cable and Ethernet cabling. Rollout: Installing new software or updates to multiple systems in a network. Router: An intelligent packet sorting device, used to route traffic on a network or between networks. Session: 1. A logical connection between two systems. It is basically an agreement that they are ready to exchange information with each other, and includes the specifics of how this will be done, for what duration, etc. 2. The period of time that a process or program is active - Each time it is opened or started marks a new session, which lasts until it is closed or halted. Computer Network Course - © 2004 Micro 2000 UK - www.micro2000.co.uk

10

Sniffer: A utility program that captures packets going over a network. SOHO network: Small Office / Home Office network, often peer-to-peer. Static addressing: Assigning a specific IP address permanently to a specific system. Compare to dynamic addressing. Subnet: A LAN that is part of a larger logical network. System administrator: A person who manages and maintains a network of computers or a large multi-user computer. TCP/IP: A suite of communication protocols used on the Internet and other networks. It stands for Transmission Control Protocol / Internet Protocol. Template: A document or other file used as a standard to create other documents and files. The template will already contain the properties and content that are common to those files created with the template so that they do not have to be re-created or re-entered each time. Throughput: A measure of the amount of data transferred in a specific amount of time, usually expressed as bits per second (bps). Tree: A way of organizing information in a hierarchy, with primary levels that have branches and sub-branches under them. Tutorial videos: A collection of video clips on the RemoteScope CD that that give a visual presentation of the more common tasks. Highly recommended for new users UNIX: Any of a group of operating systems derived from an original program written at AT&T and licensed to universities. The trademark to the name UNIX is owned by Novell, who sells a version called UnixWare. User: A person who requires a computer for the performance of a task or recreational activity. Also called an end-user User ID: The series of characters a system or network uses to distinguish one user from another. Also called a user name Virus: A program that cause damage either by deleting or corrupting files, or by interfering with computer operations by reproducing itself to fill up disk or RAM space. Originally the term applied only to the reproducing kind but it has come to mean any deliberately harmful software. Virtual Private Network: A secure connection created over a public network by using tunneling-mode encryption. Abbreviated VPN WAN: Wide Area Network. A connection between computers or networks located in separate cities or area codes Windows NT: The first full-featured network operating system from Microsoft, replaced by Windows 2000 but still in widespread use. Workgroup: A group of systems within a network that share specific resources. WWW: The World Wide Web. That portion of the Internet that uses linking HTML pages.

Computer Network Course - © 2004 Micro 2000 UK - www.micro2000.co.uk

11