Introduction to Cybersecurity

A security operations centre is the team, tooling and process that monitors an organisation's systems for security events around the clock, triages alerts, and starts the response to those that are real.

A security risk assessment identifies the threats to an organisation's assets, estimates how likely each is and how much harm it would do, and ranks them so that limited effort goes where it reduces the most harm.

Zero trust is a security model in which no request is trusted because of where it comes from, so every access to a resource is authenticated, authorised and checked against policy each time.

DHCP is the protocol by which a device joining a network asks for and receives an address, a subnet mask, a default gateway and DNS servers from a server, for a limited lease period, so that nobody has to configure addresses by hand.

A wireless LAN connects devices to a network over radio using the 802.11 family of standards, through access points that bridge the wireless medium onto the wired network and enforce the authentication and encryption that the shared airwaves demand.

TCP/IP is the family of protocols on which the internet runs: IP moves packets between addresses without guarantees, and TCP or UDP ride on top to deliver either a reliable ordered stream or fast unordered messages.

Caching keeps the result of expensive work, such as a rendered page or a database query, and serves that stored copy until it expires, making it the largest single source of speed on any busy website.

Uptime is the proportion of time a service answers requests, quoted in nines, and a service level agreement is the contract clause setting out how that proportion is counted and what the provider owes when it falls short.

Shared hosting puts your website on a machine that is simultaneously running hundreds of other people's, pooling its processor, memory and disk between all of you, which is both why it costs so little and why your speed partly depends on strangers.