AWS For Absolute Beginners: Learn AWS From Ground Up

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.

A penetration test is an authorised, scoped attempt by a skilled tester to exploit weaknesses in a system the way an attacker would, ending in a report the owner can act on.

Incident response is the prepared, practised process by which an organisation detects a security incident, contains it, removes the cause, recovers, and learns from what happened.

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.

Subnetting divides an address block into smaller networks by choosing how many leading bits identify the network, written as a prefix length or a subnet mask, so that each subnet has its own range of host addresses and its own routing entry.

Routing is how packets move between networks: each router holds a table of known destinations and the next hop toward each, learned by configuration or by a protocol, and forwards each packet to the most specific match.

A domain name is an address in the internet's public namespace that you rent through a registrar for a yearly fee, and it remains yours only while the registrar account holding it stays paid up and under your own control.

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.