knowledge

Overview

A network is a collection of interconnected devices (nodes) that communicate using links, with the purpose of sharing data, resources, and enabling collaboration. Networks range from a small home LAN to the Internet — the world’s largest WAN. All network communication follows standardized rules (protocols) and models (OSI, TCP/IP) that allow diverse devices and vendors to interoperate.

Terminology

TermDefinition
NodeAny device connected to a network (computer, printer, router, etc.)
LinkThe physical or logical connection between nodes
LAN (Local Area Network)Network confined to a small geographic area (home, office)
WAN (Wide Area Network)Network spanning large geographic distances; the Internet is a WAN
MAN (Metropolitan Area Network)Network spanning a city or metropolitan area
PAN (Personal Area Network)Short-range personal device network (e.g., Bluetooth)
NIC (Network Interface Card)Hardware that enables a device to connect to a network
TopologyThe physical or logical layout of a network
ProtocolA set of rules governing how data is formatted, sent, and received
InternetThe global WAN connecting billions of devices via standardized protocols

Core Concepts

Network Types

Networks are categorized by geographic scale and purpose.

TypeScopeExample
PANPersonal devices, short rangeBluetooth headset to phone
LANSingle building or campusHome or office network
MANCity or metropolitan areaCity-wide fiber network
WANCountry or globalThe Internet

Network Components

A functional network requires several categories of hardware and software working together.

ComponentRoleExamples
EndpointsSend and receive dataComputers, phones, printers
Intermediary DevicesRoute and direct trafficRouters, switches, hubs
NICsHardware connecting a device to the networkEthernet card, Wi-Fi adapter
MediaThe physical path data travelsCables, wireless signals
ServersRespond to requests from clientsWeb servers, file servers, DNS servers
Security DevicesMonitor and filter network trafficFirewalls, IDS/IPS
ProtocolsDefine how data is formatted, sent, and receivedTCP/IP, HTTP, DNS

Network Architectures

Different models define how devices in a network relate to each other.

ArchitectureDescriptionExample
Peer-to-Peer (P2P)All devices share resources equally; no central serverBitTorrent, small home networks
Client/ServerClients request services from dedicated serversWeb browsing, corporate networks
HybridCombines P2P and Client/Server elementsModern enterprise networks
CloudResources hosted and managed by a third-party providerAWS, Azure, Google Cloud
SDN (Software-Defined Networking)Network control is software-based and centralizedData center automation

Communication Models

Standardized models describe and organize how network communication happens.

  • OSI Model — 7-layer framework used for troubleshooting and guiding vendor development
  • TCP/IP Model — 4-layer practical implementation model used on the Internet
  • Both help vendors and developers build compatible devices and software

See OSI Model for full layer breakdown and encapsulation details.

End-to-End Data Flow

A simplified walkthrough of how data flows when a user accesses a website:

  1. DHCP — device joins the network and receives an IP address via the DORA process
  2. DNS — user types a domain name; DNS resolves it to a server IP address
  3. Encapsulation — data is wrapped in headers at each OSI/TCP-IP layer for transmission
  4. Local Transmission — data travels across the LAN to the router
  5. NAT — router translates the private IP to a public IP before sending to the internet
  6. Server Response — server receives the request, processes it, and sends a response back
  7. Decapsulation — headers are stripped at each layer; result is displayed to the user

References / Images