1.3 Network Connections and Protocols

• A computer network over a small geographical area • such as an office or a school.

• A computer network over a large geographical area. • WANs are usually made up of interconnected LANs.

Allows devices to connect to a LAN wirelessly (uses high frequency radio).

different channels run on different frequencies.

• Has a powerful central server which provides resources (such as files), • a login system • software updates to clients connected to the network. • Clients request services, the server responds.

• Computers are all at the same level and connected to each other. - There is no central server.

A network topology is the physical layout of the network (when viewed from above).

All devices (nodes) connected to all other devices (nodes)

Uses a central switch, with all devices (nodes) connected to the central switch.

allow wireless (Wi-Fi) connections to a LAN.

allow Internet connection (forwards data packets onto the Internet) and can be used to create WANs

connect devices over a LAN (using MAC addresses to get the data across the Local Area Network).

• a piece of hardware inside each computer that allows it to connect to a LAN. • NICs contain the MAC address.

Cat-5 (Ethernet cables) and fibre-optic cables.

DNS converts human-readable domain names (such as google.com) into computer-readable IP addresses (such as 243.6.83.5)

• Paying a company (such as GoDaddy) to store your website online. • They store your HTML files on their servers and allow people to view your website using their web browsers.

• simply another word for “online” storage (remote storage). • Usually you would pay a company to store your data.

using software that is being run on a remote computer (usually pay a monthly subscription to use it).

• Appears to network users like they are connected to a physical LAN or WAN without needing to be anywhere near the physical part of the network. • They need to login with a username and password. • Once logged in, they can access files, folders and software as though they were physically in the same building as the network.

• A protocol and set of standards for communicating over a Local Area Network. • The Ethernet protocol controls how data is sent and received across a Local Area Network as well as the connectors and cabling.

HTTP allows web browsers to request websites from web servers (this runs on port 80).

HTTPS is the secure (encrypted) version of HTTP, suitable for exchanging sensitive information, e.g. bank details.

• FTP allows large files and folders to be transferred across the Internet. • Website developers might use this to upload their HTML files to be hosted on a web server.

Allows users to download an email once only. - When it has been downloaded, it is removed from the email server.