Cisco CCNA 200-301 – The Complete Guide to Getting Certified

An intrusion detection system watches network traffic or host activity for signs of attack and raises alerts, while an intrusion prevention system sits inline and can block what it recognises.

A SIEM collects logs and events from across an organisation's systems into one searchable store, correlates them into alerts, and retains them for investigation and compliance.

Vulnerability management is the continuous process of finding weaknesses in systems, deciding which ones matter in context, fixing or mitigating them, and confirming the fix.

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.

The OSI model is a seven-layer reference framework that separates networking into physical transmission, link, network, transport, session, presentation and application concerns, used to reason about where a problem sits rather than to describe any real protocol stack.

IP addressing is the scheme that gives every interface on a network a numeric address, with IPv4's four-byte addresses now supplemented by IPv6's much larger space, and with private ranges reserved for use inside networks that reach the internet through translation.

Cloud hosting is the model in which servers, storage and databases are created on demand through an API from a provider's pooled hardware and billed for the time they exist, rather than rented as a fixed box by the month.

A web server is the program listening on a network port for HTTP requests and answering them, either by returning a file from disk or by handing the request to application code behind it.

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.