CIS105: Computer Applications & Information Systems Lect. 8 ​

Chapter 8: Computer Networks ​

8.1: Computer Networks ​

• Two or more computers connected together to share resources like:
• Folders and files
• Software
• Hardware
• Scanners, Printers, Webcams, etc. Consider a network made up of three computers (Clients) connected to one computer called a Server. The server is connected to a printer and a scanner (peripheral devices) enabling all three clients to use them. Any device connected to a network is called a node.

8.2: Building a Computer Network ​

All networks require four basic components

1. Network Interface Controller Card (NIC): Plugged into the motherboard to interface and connect with other computers.
2. Protocol: TCP/IP controls how data and information is shared between computers.
3. Cables: Cables connect servers to clients which can sometimes be replaced through wireless connections.
4. Hub: Typically, the central location of a network (server) that serves to run the network smoothly

8.3: Network Protocols ​

Provides a common language and rules for communication between computers. A protocol is a convention or standard that controls or allows communication and data transfer between two computers.

• Transmission Control Protocol / Internet Protocol (TCP/IP): When sending a file from one computer to another, the file is broken down into smaller files called “packets”. The packets arrive at the receiving computer and must be reassembled correctly to guarantee the receiving computer gets a file that will work (not corrupted).
• User Datagram Packets: Break large files into packets, but unlike TCP/IP, allows a user to use the incoming file.

8.4: Network Operating Systems ​

A Network Operating System (NOS) is similar to a stand-alone platform but responsible for much more:

• Automatic hardware detection. The NOS recognizes it when it becomes part of the network.
• Supports multi-processing which allows several processes to occur at one time.
• Recognizes who is using the network.
• Provides security

8.5: Network Administrator ​

• Responsible for smooth network operations
• Network performance
• Implementation of new nodes and users
• Strong business background

8.6: Network Topology ​

Refers to the mapping of a physical network and logical interconnections between nodes. Basically, the way a network is arranged and laid out.

• Bus Topology: Sometimes called a linear bus topology where the network’s nodes are connected to a common linear backbone with tw endpoints. If the backbone fails, the whole network fails.
• Star Topology: One central server in which clients connect in a spoke- like fashion, or star. If the server fails, the network fails. (Most common topology)
• Ring Topology: Data is transferred between computers in a circular manner.

8.7: Types of Computer Networks ​

• Local Area Network (LAN): A small network typically confined by a single building. Often used by smaller businesses.
• Campus Area Network (CAN): Connects two or more LANs which are located on universities or large businesses.
• Metropolitan Area Network (MAN): A computer network that connects CANs and LANs into a larger network like a city.
• Wide Area Network (WAN): Connects LANs, CANs, and MANs and can cover an entire country
• Peer to Peer (P2P): Generally, connect computers to each other.
• Internet: The world’s largest network interconnecting public, private, commercial, and governmental networks. Network Security Starts with a solid understanding of network threats. Network administrators must adopt policies which define rules for network access.
• Passwords: A secret word or combination of keyboard characters typed in by the user to authenticate their identity to a network and gain appropriate access.
• Strong Passwords: Same as passwords, but requires a user to use upper case characters, lower case characters, numbers, and special characters.
• Passphrase: Same as a Strong Password, but a phrase that is memorable.

8.8: Network Security ​

• Web Browsing on a Network: Part of network security includes policies and procedures regarding employee’s web browsing. Should a business let employees browse on the Web?
• Email / Instant Messaging: On a business network, consider that all email and instant message is recorded and saved, therefore, policies and procedures must be in place regarding appropriate usage.
• Permissions: Network access is called “permissions”, which grants and denies access to a network depending on the user.
• Firewall: Hardware and software on a proxy server that determines who is allowed on a network, and who is not.

8.9: Green Business Computing Plan ​

Based on the idea that businesses can be environmentally friendly, more profitable, and socially responsible.

• Organizational policies and procedures
• Best Practice considerations
• Long term, sustainable considerations
• Reduction of power usage and paper consumption
• Recycling policies and procedures
• Used computer software and hardware disposal
• EPEAT and Energy Star® compliance
• Green PC purchasing recommendations