CCIE Routing & Switching Version 5.0 -IP Services - QoS

Authentication is the process of confirming that a user, device or service is who it claims to be, typically by checking something it knows, has or is.

Multi-factor authentication requires proof from at least two different kinds of factor, such as a password and a device-generated code, so that stealing one is not enough to log in.

Identity and access management is the set of policies and systems that create, verify, govern and retire identities and decide what each one may reach.

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.

Switching is the forwarding of frames within a single network segment by a device that learns which hardware address sits on which port and sends each frame only where it needs to go.

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.

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.

A VPS is a software-defined slice of one physical machine that behaves as a server in its own right, with its own operating system, reserved CPU, memory and disk, and administrative access down to the kernel.

A dedicated server is an entire physical computer rented by a single customer, with no hypervisor taking a share and no other tenants on the hardware, chosen when consistent performance, specific components or provable isolation matter more than the ability to resize in seconds.