J277 Section 3 Computer Networks, Connections and Protocols

Internet

A global network of interconnected computers that communicate using standardized protocols, allowing for data exchange and access to information across the world. The largest example of a WAN.

LAN

A local area network that connects computers within a limited geographical area, such as a home, school, or office, enabling resource sharing and communication. Hardware is typically owned by the organisation.

WAN

Multiple LANs connected over large distances, allowing users to communicate and share resources across greater geographical areas. Hardware is often owned by multiple organizations or service providers.

WWW

A system of interlinked hypertext documents accessed via the Internet, using web browsers to view and navigate content.

IP address

A unique string of numbers assigned to each device connected to a computer network that uses the Internet Protocol for communication.

IP v4 format

A 32-bit numerical format for IP addresses, typically represented as four decimal numbers separated by periods, allowing for approximately 4.3 billion unique addresses. For example 192.168.1.1.

IP v6 format

A 128-bit numerical format for IP addresses, typically represented as eight groups of four hexadecimal digits separated by colons, allowing for a vastly larger number of unique addresses compared to IPv4. For example 2001:0db8:85a3:0000:0000:8a2e:0370:7334.

URL

A URL (Uniform Resource Locator) is the address used to access resources on the Internet, specifying the location of a resource and the protocol used to retrieve it, such as HTTP or HTTPS.

Domain Name

A human-readable address that corresponds to an IP address, used to identify a resource on the Internet, such as www.example.com.

Domain Name System

A hierarchical system that translates human-readable domain names into IP addresses, allowing users to access websites using easy-to-remember names instead of numerical addresses.

DNS process

When a user enters a URL in their web browser, the browser checks its cache for the IP address. If it's not found, the request is sent to a DNS resolver, which queries a root DNS server. The root server responds with the address of a Top-Level Domain (TLD) server for the requested domain. The resolver then queries the TLD server, which replies with the address of the authoritative DNS server for the specific domain. Finally, the resolver contacts the authoritative server, retrieves the IP address, and returns it to the browser. The browser then uses the IP address to access the requested resource.

MAC address

A unique identifier assigned to a network interface controller (NIC) for communications on a network. It is used to ensure that data packets are delivered to the correct device on a local network.

MAC Address format

A MAC address is typically expressed as six pairs of hexadecimal digits, separated by colons or hyphens, such as 00:1A:2B:3C:4D:5E.

NIC

A Network Interface Controller is a hardware component that connects a computer to a network, enabling communication and data exchange over that network.

Ethernet

A family of protocols used for local area networks (LANs), enabling devices to communicate over a wired connection.

Wireless

A technology that allows devices to connect to a network without physical cables, using radio waves for communication.

Bluetooth

A wireless technology that enables short-range communication between devices, allowing data transfer and connection without cables.

Circuit Switching

A method of communication where a dedicated communication path is established between two devices for the duration of the transmission, ensuring a constant and reliable connection (used in phone calls for example).

Packet Switching

A method of data transmission where data is broken into packets and sent over a network, allowing multiple communications to occur simultaneously and efficiently.

Packet

A unit of data formatted for transmission over a network, containing both payload and control information.

Header

A part of a data packet that contains control information such as the source and destination addresses, as well as other metadata necessary for routing and delivery.

Benefits of networks

The advantages of using networks include resource sharing, improved communication, enhanced collaboration, and centralized data management.

Drawbacks of networks

The disadvantages of using networks include security vulnerabilities, potential for data loss, dependency on network infrastructure, and increased complexity in management.

Topology

The arrangement of different elements in a network, including how devices are connected and communicate with each other. Common types include star, ring, and bus topologies.

Star topology

A network topology where all devices are connected to a central hub or switch. This configuration allows for easy addition and removal of devices without disrupting the network.

Mesh topology

A network topology where each device is connected to multiple other devices, allowing for multiple pathways for data to travel. This redundancy enhances reliability and fault tolerance.

Full mesh

A type of mesh topology where every device is directly connected to every other device in the network, providing maximum redundancy and fault tolerance.

Partial Mesh

A network topology where some devices are connected to multiple other devices, but not all devices are interconnected. This provides a balance between redundancy and cost, enhancing performance while reducing complexity.

Bus topology

A network topology where all devices are connected to a single central cable, known as the bus, allowing data to travel in both directions along the cable.

Ring topology

A network topology where each device is connected to exactly two other devices, forming a circular pathway for data to travel. This structure allows data to circulate in one or both directions, but a failure in any single connection can disrupt the entire network.

Router

A device that forwards data packets between computer networks, directing traffic on the internet by determining the best path for data transmission.

Switch

A device that connects multiple devices within a local area network (LAN), using packet switching to receive, process, and forward data to the destination device.

Transmission media

The physical pathways through which data signals are transmitted in a network, including cables, optical fibers, and wireless signals.

Ethernet cable

A type of transmission media used to connect devices in a wired local area network (LAN), allowing for the transfer of data at high speeds.

Twisted pair copper cable

A type of transmission media consisting of pairs of insulated copper wires twisted together, commonly used in networking for connecting devices and transmitting data.

Fibre-optic cable

A type of transmission media that uses light to transmit data through thin strands of glass or plastic, enabling high-speed data transfer over long distances with minimal signal loss.

Coaxial cable

A type of transmission media that consists of a central conductor, insulating layer, and outer conductive shield, commonly used for cable television and internet connections.

WAP

A Wireless Access Point (WAP) is a networking device that allows wireless devices to connect to a wired network using Wi-Fi or other standards.

Fibre-optic range

refers to the distance over which data can be transmitted using fibre-optic cables without significant loss of signal quality, typically extending several kilometers depending on the technology used.

Ethernet cable range

refers to the maximum distance over which Ethernet cables can transmit data effectively, typically up to 100 meters for standard twisted pair cables, depending on the category of the cable used.

WiFi range

refers to the maximum distance over which wireless devices can connect to a Wi-Fi network, typically ranging from a few dozen meters indoors to several hundred meters outdoors, depending on the environment and the access point used.

Bluetooth Range

refers to the maximum distance over which Bluetooth devices can communicate wirelessly, typically up to 100 meters depending on the class of the Bluetooth technology used.

Encryption

is the process of converting data into a coded format to prevent unauthorized access, ensuring confidentiality and data integrity during transmission.

Plaintext

the original, unencrypted data that is input into an encryption algorithm before being transformed into ciphertext.

Ciphertext

is the result of encryption, representing data that has been transformed from plaintext into a coded format, making it unreadable without the appropriate decryption key.

Key

a piece of information used in encryption algorithms to encode or decode data, ensuring that only authorized users can access the original plaintext.

Symmetric encryption

is an encryption method where the same key is used for both encryption and decryption, allowing for secure communication between parties who share the key.

Asymmetric Encryption

is an encryption method that uses a pair of keys, a public key for encryption and a private key for decryption, enabling secure communication without sharing the private key.

Client-server network

is a network architecture where client devices request resources or services from centralized servers, which manage and provide these resources.

Peer-to-peer network

is a decentralized network architecture where each participant (peer) can act as both a client and a server, allowing for direct sharing of resources and services without a central server.

Server

a powerful computer or system that provides resources, data, services, or programs to other computers, known as clients, over a network.

Client

a device or application that requests services or resources from a server in a client-server network.

File server

a server that stores and manages files, allowing clients to access and share data over a network.

Email Server

a server that manages and stores email messages, allowing users to send, receive, and store their emails.

Web server

a server that stores, processes, and delivers web pages to clients over the internet, using protocols like HTTP.

Web hosting

a service that allows individuals or organizations to post a website or web page onto the Internet, providing the necessary technologies and services.

File Transfer Protocol

a standard network protocol used to transfer files from one host to another over a TCP-based network, such as the Internet.

Domain Name Registration

the process of acquiring a unique name for a website, which is then linked to an IP address, allowing users to easily access the site.

Cloud

a model of computing that enables on-demand access to a shared pool of configurable computing resources, such as servers, storage, applications, and services over the Internet.

Factors affection Network Performance

Elements that influence the speed, reliability, and efficiency of data transmission across a network, including bandwidth, latency, interference and network congestion.

Protocol

a set of rules and conventions that govern how data is transmitted and received over a network, ensuring proper communication between devices.

Network Standard

a set of guidelines and specifications that ensure compatibility and interoperability among different devices and systems in a network.

Transmission Control Protocol/Internet Protocol (TCP/IP)

a suite of communication protocols used to interconnect network devices on the internet, providing reliable transmission of data.

Hypertext Transfer Protocol (HTTP)

a protocol used for transferring hypertext requests and information on the internet, enabling web browsing.

Hypertext Transfer Protocol Secure (HTTPS)

an extension of HTTP that adds a layer of security by using SSL/TLS to encrypt data transmitted over the web.

File Transfer Protocol (FTP)

a standard network protocol used for transferring files between a client and a server over a computer network.

Post Office Protocol (POP)

a protocol used by email clients to retrieve emails from a remote server, allowing users to download messages for offline access. It typically deletes emails from the server after retrieval.

Internet Message Access Protocol (IMAP)

a protocol used by email clients to retrieve emails from a remote server while keeping messages on the server for access from multiple devices. Unlike POP, IMAP allows for better management of emails and synchronization across devices.

Simple Mail Transfer Protocol (SMTP)Layers

a protocol used for sending emails from a client to a server, facilitating the transmission of messages across the Internet.

Network Layers

The layers of a network architecture that define how data is transmitted over a network, including the link, internet, transport and application layers.

Benefits of layers

The benefits of layers in network architecture include improved organization, easier troubleshooting, enhanced scalability, and the ability to implement changes in one layer without affecting others. This modular approach simplifies network design and management.

Application layer

Encodes the data being sent so that it is understandable by the recipient and facilitates communication between software applications over the network.

Transport Layer

This layer is responsible for splitting data into packets and adding packet information so they can be reassembled correctly.

Internet Layer

The Internet Layer is responsible for routing packets across multiple networks, attaching the IP addresses of the sender and destination and ensuring that data is sent from the source to the destination through various intermediary devices, and defining the addressing scheme used for devices on the network.

Link Layer

This layer is responsible for attaching the MAC addresses of the sender and recipient, allowing the packet to be properly directed to the correct device on the local network and managing the physical transmission of data over the network medium.