Computer Networking Flashcards
Computer communications
The process of sharing data programs and information between two or more computers
Eg email, electronic commerce, video conferencing
Concepts
Connectivity: a concept related to using computer networks to link people and resources
Communication systems: electronic systems that transmit data from one location to another
Elements of a communication systems
Sending and receiving devices
Connection devices
Data transmission specifications
Communication channel
Communication channels
An essential element of every communication system
Carry the data from one computer to another
Categories:
Physical/wired connection
Wireless
Physical connections
Twisted pair cable: consists of pairs of copper wire that are twisted together. Used for telephone and network connections. Standard telephone lines and Ethernet cables use twisted pair
Coaxial cable: a copper cored network cable surrounded by a heavy shielding. Used to deliver television signals as well as to connect computer in a network
Fibre optical cable: transmits data as pulses of light through tiny tubes of glasses. It’s lighter, faster and more reliable transmitting data. Rapidly twisted pair cable telephone lines. Not affected by electro magnetic radio frequency interference
Wireless connections
Do not use a solid substance to connect sending and receiving devices. They move through the air
Use radio, microwaves, infrared signals. Use radio waves to communicate
Short range: Bluetooth
Medium range: WiFi
Longer range: WiMAX
Networks
Computer network is a communication system that connects two or more computers so that they can exchange information and share resources.
Benefits of networking
Fewer peripherals needed Increased communication capabilities Avoid file duplication Lower cost if licensing Centralised administration Conservation of resources
Key terms
Node: any device that is connected to a network. It could be a computer, printer or data storage device
Client: a node that requests and suses resources available from other node’s
Server: a node that shares resources with other nodes
Directory server: a specialised server that manages resources such as user accounts for an entire network
Host: any computer system connected to a network that provides access to its resources
Network Adapter/Network Interface Card (NIC): used to connect a PC to a network or the Internet. Called NIC when in the form of an expansion card. Built in protable computers.
Network architecture
Peer to peer networks: devices which are connected directly to each other without any additional networking devices between them. Nodes have equal authority and can act as both clients and servers
Client/server networks: client requests information or servhce from the server. The server provides the requested information or service to the client
Networks types
Local Area Network: networks with nodes that are in close physical proximity eg within the same building. Widely used by colleges, universities and other types of organisations. Network gateway is advice that allows one LAN to be linked to other LANs or to larger networks
Wireless LAN: a group of wireless devices that connect to access points within a specified area
Personal Area Network: network that connects devices such as keyboards, mice, printers, smartphones and tablets within the range of an individual person. Often connected with Bluetooth tech.
Metropolitan Area Network: frequently used as links between office buildings that are located thought a city
Wide Area Network: provide access to regional services providers and typically span distances greater than 100 miles. Use microwave relays and satellites to reach users over long distances
Bandwidth
The amount of data that can be transmitted within a fixed time period
Measures in bits per second
Latency
Amount of time it takes data to travel from source to destination
Data transmission
Simplex: a single one way transmission
Half duplex: allows data to flow in one direction at a time
Full duplex: allows data to flow in both directions at the same time
Physical network components
Modem
Network devices:
Computers
Hubs and repeaters. A hub is a central device that connects all of the devices on the network. Repeater amplifies signals along a network.
Bridges and switches. A bridge has the intelligence to determine if an incoming frame is to be sent to a different segment or dropped. Has two ports. A a switch has several ports and refers to a table of MAC addresses to determine which port to use to forward the frame.
Routers. Devices that connect entire network to each other. They use IP addresses to fowdd packets to other networks.
Repeaters
Wireless access points. Provide network access to wireless devices such as laptops and PDAs.
Network media:
Twisted pair copper cable has
Fibre optic cabling
Radio waves
Network topologies
Bus network: each device is connected to a common cable called a bus or backbone and all communications travel along this bus.
Ring network: each device is connected to two other devices forming a ring
Star network: each device is connected directly to a central network switch. The most widely used. It is applied to a broad range of applications from small networks in the home to very large networks in major corporations.
Tree network: each device is connected to a central node either directly or through one or more other devices. Often used to share corporate wide data.
Mesh network: requires that each node have more than one connection to the other nodes. Connects all devices to each other.
Organizational networks
Intranet: a private network within an organisation that resembles the Internet. Main purpose is to share company information information computing resources among employees. Use browsers, websites and Web pages
Extranet: a private network that connecsf more than one organisation. Many organisations use it to allow suppliers and others limited access to their networks. The purpose is to increase efficiency and reduce costs. Requires security and privacy
IP addressing
An IP address is a unique number that is used to underlying a network device and is represented as a 32 bit binary numbers divided into four octets.
Internet protocols
A protocol is a set of rules. Theg government communication within and between computers on a network.
Eg HTTP (hypertext transfer protocol secure) to protect the transfer of sensitive information
FTP is used for file transfer (File Transfer protocol)
SMTP (simple mail transfer protocol) to exchange mail with other email servers throughout the world
TCP/IP for communication
Functions of protocols:
Identifying errors Compressing data Deciding how data is to be sent Addressing data Deciding how to announce sent and received data
Network security
Firewalls: monitors and controls incoming and outgoing network traffic based on pre determined security rules
Intrusion detection systems: used sophisticated statistical techniques to analyse all incoming and outgoing network traffic. Can recognize signs of a network attack and disable access before an intruder can do damage
Virtual private networks: crates a secure private connection between a remote user and an organizagiond internal network
