Networks

standalone machine

a single computer, not connected to anything else

network

connecting one computer device to another, either via cable or wireless

LAN

• local area network

• a network that covers a small geographical area

• connected using UTP cable, fibre optic, wifi

WAN

• wide area network

• a network that covers a large geographical area

• multiple LANs in different areas connect = WAN

• connected using telephone lines, fibre optic cables, satellite links

modem

• transforms digital info from a computer into analogue signals that are transmitted through wires

router

• routes data between devices on a network and the internet

twisted pair cable

• made up of a pair of insulated copper wires

• more affordable than coaxial and fibre optic cables

• used for telephone networks, data networks and cable shielding

coaxial cables

• made up of

• a solid conductor wire

• a layer of insulation

• a grounding conductor

• a layer of exterior insulation

fire optic cables

• made up of very thing optical fibres bundled together into a single cable

• highest noise immunity

• more expensive than twisted pair and coaxial cables

• used to support long-distance connections between cities and countries

NIC

• network interface controller

• allows wired and wireless communications between computers on a LAN, or connected to a large-scale network using the internet protocol (IP)

WAP

• wireless access point

• a device that creates a wireless local area network (WLAN)

• connects to a wired router, switch or hub via an ethernet cable

hub

• allows you to connect multiples devices to one network

• operates on the physical layer, is considered a passive device

• much slower than switches in terms of data transfer

switch

• allows you to connect multiple devices to one network

• operates on the data link layer, is an active device

• faster than hubs in terms of data transfer

circuit switching

• physical path between source and destination

• all packets use the same path

• reserves bandwidth in advance

• can cause a lot of bandwidth wastage

• no store and forward transmission

packet switching

• no physical path between source and destination

• packets travel independently

• does not reserve bandwidth

• no bandwidth wastage

• supports store and forward transmission

TCP

• transmission control protocol

• provides error free transmission between two routers

IP

• internet protocol

• routes packets across a WAN

UDP

• user datagram protocol

• an alternative to TCP, but has no error checking

• sends short messages using datagrams, where speed is more important than accuracy

HTTP

• hypertext transfer protocol

• a way for a client and server to send and receive requests and deliver HTML web pages

• HTTPS (secure) adds encryption and authentication

FTP

• file transmission protocol

• used for sending files between computers on a WAN

POP

• post office protocol

• retrieves emails from a mail server and transfers them to your device, removing them from the server in the process

IMAP

• internet message access protocol

• keeps emails on the mail server, maintains synchronicity between devices

SMTP

• simple mail transfer protocol

• transfers outgoing emails between servers and from email clients to servers

application layer (four-layer TCP/IP protocol model)

• network applications such as web browsers or email programs operate at this layer

• FTP, HTTP, HTTPS, SMTP, IMAP

transport layer (four-layer TCP/IP protocol model)

• sets up communication between two hosts — they agree settings such as language and packet size

• TCP, UDP

internet/network layer (four-layer TCP/IP protocol model)

• addresses and packages data for transmission, routes packets across the network

• IP

link layer (four-layer TCP/IP protocol model)

• network hardware and connection port standards. operating system device drivers also sit here. facilitates the transmission of binary via any media

• copper twisted pair, fibre, wifi

domain name system

1. user requests a URL via a browser

2. browser sends the domain name to a domain name system (DNS)

3. the DNS maps the domain name to an IP address and returns it to the browser

4. a GET request for the web page or resource is returned to the client’s web browser