OCR ALevel CS: 1.3.2 Networks

“A set of rules that allow two devices to communicate.” 

• Protocol
• Peer to Peer
• Client-Server
• Encryption
• Proxies

Transmission Control Protocol / Internet Protocol: “The most common general-purpose standard protocol that allows any networked computers (including those on The Internet) to communicate with each other whatever their equipment.” 

• TCP/IP Stack
• Protocol
• Peer to Peer
• Client-Server
• Encryption

Domain Name System: “The Internet’s equivalent of a phone book.  They maintain a directory of domain names and translate them to Internet Protocol (IP) addresses.  This is necessary because, although domain names are easy for people to remember, computers or machines access websites based on IP addresses.” 

• DNS
• TCP/IP Stack
• Protocol
• Peer to Peer
• Client-Server

“The concept of a protocol not simply being a set of rules but those rules being built up into very specific layers and those rule layers behind built on top of each other in a deliberate order creating a layered protocol stack.  This results in the rules of a protocol being executed in a specific sequence as you move through the protocol stack.” 

• Protocol Layering
• DNS
• TCP/IP Stack
• Protocol
• Peer to Peer

Local Area Network: “A collection of computers / computing devices on the same network which are physically close together, for example, all located within one  building or site e.g. a home or school network.” 

• LAN
• Protocol Layering
• DNS
• TCP/IP Stack
• Protocol

Wide Area Network: “A collection of computers / computing devices on the same network which are spread out over a geographically large area, for example a university across several campuses, or a multinational corporation with offices / sites in different cities or even different countries.” 

• WAN
• LAN
• Protocol Layering
• DNS
• TCP/IP Stack

“A method of sending data over a wide area network in which the message is broken into a number of parts which are sent independently, over whatever route is optimum for each packet, and reassembled at the destination.” 

• Packet Switching
• WAN
• LAN
• Protocol Layering
• DNS

“A method of sending data over a wide area network in which two network nodes establish a dedicated communications channel through the network before the nodes may communicate.  All data then follows this same path for the duration of the data transfer.” 

• Circuit Switching
• Packet Switching
• WAN
• LAN
• Protocol Layering

“A computer application used in a network to prevent external users gaining unauthorised access to a computer system.” 

• Firewall
• Circuit Switching
• Packet Switching
• WAN
• LAN

“A computer application that accesses data on a different computer system or network.  It controls the access of authorised users to data and allows the operation of the system to be isolated from control by external users.” 

• Proxies
• Firewall
• Circuit Switching
• Packet Switching
• WAN