Cisco CCNA 200-301 Complete A-Z Cisco CCNA Networking Course

Phishing is an attack that deceives a person into revealing credentials, approving a payment or running malicious content, usually through a message that impersonates someone they trust.

Ransomware is an attack in which criminals gain access to an organisation's systems, encrypt or steal its data, and demand payment to restore access or withhold publication.

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 VLAN divides one physical switched network into several logical segments, each with its own broadcast domain, by tagging frames with a VLAN identifier so that ports and devices in different VLANs cannot reach each other without a router.

Network address translation rewrites the addresses and ports in packets as they cross a network boundary, most commonly so that many devices with private addresses can share one public address to reach the internet.

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.

IaaS is the layer of cloud computing where you rent raw infrastructure through an API, meaning virtual machines, disks and networks, and take responsibility for the operating system and everything you install above it.

PaaS is a hosting layer that takes your source code and turns it into a running application for you, owning the machines, the runtime, the build, the routing, the certificates and the restarts, so that shipping becomes a push rather than a project.

Serverless computing runs your code only while an event is calling it: the provider conjures an execution environment on demand, throws it away afterwards, and charges for work performed instead of for capacity sitting idle.

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.