CompTIA Exam Prep - ITF+, A+, Network+, Security+, CySA+

MPLS forwards packets by a short fixed-length label rather than by looking up a destination address. The label is decided once, at the edge, and every device after that makes a simple lookup in a much smaller table. It is frequently called a layer 2.5 protocol, because the label sits between the layer 2 header and the layer 3 packet. That is a useful way to remember where it lives, though the real point is that MPLS is indifferent to what it carries. How a Packet Moves Two device roles: LER (Label Edge Router) sits at the boundary. The ingress LER classifies an incoming packet, decides its path, and pushes a label. The egress LER pops the label and forwards the packet normally. LSR (Label Switch Router) sits in the core. It reads the incoming label, swaps it for the outgoing one, and forwards. It never inspects the IP header. The path a labelled packet follows is a Label Switched Path , and it is unidirectional — return traffic takes its own LSP, which may be a diff...

A wide area network connects networks across large geographic distances — between cities, countries, or continents. The definition every exam wants is short: a WAN spans a broad area and typically relies on infrastructure the organization does not own. The defining characteristic of a WAN is not distance. It is that someone else owns the links. That ownership point is what actually separates a WAN from a LAN. On a LAN you own the switches and the cable, so bandwidth is cheap and you control everything. On a WAN you lease capacity from a carrier, which makes bandwidth expensive, latency a fact of physics you cannot negotiate away, and availability something you buy in a contract rather than engineer yourself. The Network Types by Scale Type Scope Example PAN — personal area network A few metres Bluetooth headset, Wi-Fi Direct LAN — local area network A building or floor Office Ethernet and Wi-Fi CAN — campus area network Several adjacent buildings A university or hospita...