CCIE Routing & Switching Version 5.0 - Layer 2

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.

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.

Kubernetes is an open-source system that runs containers across a cluster of machines, keeping the number and placement of running copies matched to a declared desired state, and restarting, rescheduling and scaling them without a person intervening.

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.