Glossary · Networking410 GoneA 410 Gone response tells clients that a resource was permanently removed on purpose and no replacement address exists.Glossary · Networking802.1X (Port-Based Network Access Control)802.1X is an IEEE standard that blocks a network port until the connecting device authenticates, commonly with a RADIUS server.Glossary · NetworkingAccess Point (Wireless AP)A wireless access point is a device that connects Wi-Fi clients to a wired network, acting as the bridge between radio and Ethernet.Glossary · NetworkingAnycast RoutingAnycast announces the same IP address from many locations, so network routing sends each user to a nearby site and absorbs traffic floods.Glossary · NetworkingAPIPA (Automatic Private IP Addressing)APIPA is the fallback in which a device without a DHCP answer assigns itself an address in 169.254.0.0/16 for local-only communication.Glossary · NetworkingARP (Address Resolution Protocol)ARP is the protocol IPv4 hosts use to find the MAC address that belongs to an IP address on the same local network.Glossary · NetworkingASN (Autonomous System Number)An ASN is a unique number assigned to a network operator that identifies its routing domain in BGP on the public Internet.Glossary · NetworkingBGP (Border Gateway Protocol)BGP is the routing protocol that exchanges reachability information between autonomous systems and decides how traffic flows across the Internet.Glossary · NetworkingBroadcastBroadcast is a transmission delivered to every device on a local network segment, used for discovery tasks such as ARP and DHCP requests.Glossary · NetworkingCable BroadbandCable broadband delivers internet over the coaxial TV network using DOCSIS, with neighbourhood bandwidth shared among many subscribers.Glossary · NetworkingCanonical RedirectA canonical redirect permanently sends every variant of a URL, such as http, www or trailing-slash versions, to one preferred address.Glossary · NetworkingCaptive PortalA captive portal is a web page that intercepts a new network connection, typically public Wi-Fi, until the user logs in or accepts terms.Glossary · NetworkingCGNAT (Carrier-Grade NAT)CGNAT is NAT performed by an internet provider that lets many customers share a small pool of public IPv4 addresses.Glossary · NetworkingCIDR (Classless Inter-Domain Routing)CIDR is the notation and method for writing IP ranges as an address plus a prefix length, such as 203.0.113.0/24, instead of fixed address classes.Glossary · NetworkingClient Error (4xx)A 4xx response means the server understood the request but will not or cannot fulfill it because of a problem the client can fix, such as a bad URL or missing login.Glossary · NetworkingCongestion ControlCongestion control is the set of algorithms, mainly in TCP, that adjust sending rate to avoid overloading network links and routers.Glossary · NetworkingConnection DrainingConnection draining lets a load balancer stop sending new requests to an instance while allowing its existing connections to finish before removal.Glossary · NetworkingDefault GatewayA default gateway is the router address a device sends traffic to when the destination is outside its own subnet, usually the path to the Internet.Glossary · NetworkingDHCP (Dynamic Host Configuration Protocol)DHCP is a protocol that automatically gives devices an IP address, subnet mask, default gateway and DNS servers when they join a network.Glossary · NetworkingDMZ (Demilitarized Zone)A DMZ is a separate network segment that holds public-facing servers, isolating them from the internal network behind additional firewall rules.Glossary · NetworkingDownstreamDownstream describes services or clients that receive requests, data or failures from a component, as opposed to the upstream it depends on.Glossary · NetworkingDSL (Digital Subscriber Line)DSL delivers broadband internet over ordinary copper telephone lines, with speed falling as the distance to the exchange grows.Glossary · NetworkingDual Stack (IPv4 and IPv6)Dual stack means a device or network runs IPv4 and IPv6 side by side, so each connection can use whichever protocol the destination supports.Glossary · NetworkingDuplex (Half and Full Duplex)Duplex describes whether a link can send and receive at the same time (full duplex) or only one direction at a time (half duplex).Glossary · NetworkingEthernetEthernet is the dominant wired networking technology, defining how devices send frames over copper or fiber links in local networks.Glossary · NetworkingFiber Optic (Optical Fiber)Fiber optic cables carry data as pulses of light through thin glass strands, giving high bandwidth, low signal loss and long reach.Glossary · NetworkingFirewallA firewall is software or hardware that allows or blocks network traffic according to rules based on addresses, ports and protocols.Glossary · NetworkingForward ProxyA forward proxy is a server that makes requests to the internet on behalf of clients, hiding or filtering their traffic.Glossary · NetworkingFTP (File Transfer Protocol)FTP is an old, unencrypted protocol for moving files between a client and server using separate control and data connections.Glossary · NetworkingGRE (Generic Routing Encapsulation)GRE is a simple tunneling protocol that wraps many kinds of network packets inside IP, without providing any encryption on its own.Glossary · NetworkingHop CountHop count is the number of routers a packet passes through between source and destination, limited in practice by the IP TTL field.Glossary · NetworkingHTTP Keep-Alive TimeoutThe HTTP keep-alive timeout is how long a server holds a persistent connection open waiting for the client's next request.Glossary · NetworkingHTTP Status CodeAn HTTP status code is the three-digit number in a server response that tells the client whether a request succeeded, was redirected or failed, and why.Glossary · NetworkingHTTP Status Code ClassA status code class is the first digit of an HTTP status code, which groups responses into informational, success, redirection, client error and server error.Glossary · NetworkingICMP (Internet Control Message Protocol)ICMP is the IP companion protocol that carries error reports and diagnostic messages, such as echo requests used by ping and unreachable notices.Glossary · NetworkingIdle TimeoutAn idle timeout is how long a connection can sit with no data flowing before a server, proxy or load balancer closes it.Glossary · NetworkingIP Address Classes (Classful Addressing)IP address classes were the original IPv4 scheme dividing addresses into classes A to E by leading bits, later replaced by CIDR.Glossary · NetworkingIP FragmentationIP fragmentation splits a packet larger than a link's MTU into smaller pieces that the destination host reassembles.Glossary · NetworkingIPsec (Internet Protocol Security)IPsec is a suite of protocols that authenticates and encrypts IP packets, widely used for site-to-site and remote-access VPNs.Glossary · NetworkingIXP (Internet Exchange Point)An IXP is a physical facility where many networks connect to exchange traffic with each other directly, usually through a shared switch fabric.Glossary · NetworkingJitterJitter is the variation in delay between packets arriving at a destination, which disrupts real-time voice, video and gaming traffic.Glossary · NetworkingLAN (Local Area Network)A LAN is a network that connects devices within a limited area, such as a home, office or building, typically using Ethernet or Wi-Fi.Glossary · NetworkingLDAP (Lightweight Directory Access Protocol)LDAP is a protocol for querying and updating hierarchical directories of users, groups and devices, widely used for centralized authentication.Glossary · NetworkingLeased LineA leased line is a dedicated, symmetric private connection rented from a carrier, giving guaranteed bandwidth and service levels between two points.Glossary · NetworkingLink Aggregation (LACP)Link aggregation bundles several physical network links into one logical link to increase capacity and provide failover, often via LACP.Glossary · NetworkingLoad BalancerA load balancer distributes incoming traffic across multiple servers, using health checks to route around failures and improve availability and capacity.Glossary · NetworkingLoopback AddressThe loopback address is a special IP, 127.0.0.1 in IPv4 and ::1 in IPv6, that lets a computer send network traffic to itself without leaving the machine.Glossary · NetworkingMAC AddressA MAC address is a 48-bit hardware identifier assigned to a network interface and used to deliver Ethernet and Wi-Fi frames on the local link.Glossary · NetworkingMesh NetworkA mesh network is a topology where multiple nodes connect to each other and relay traffic, so coverage and resilience improve without a single central link.Glossary · NetworkingModemA modem is a device that converts digital data into the signal type of a physical line, such as cable, DSL or fiber, and back again.Glossary · NetworkingMPLS (Multiprotocol Label Switching)MPLS forwards packets across a carrier network using short labels instead of full IP lookups, enabling private WANs with predictable performance.Glossary · NetworkingMTU (Maximum Transmission Unit)MTU is the largest packet size in bytes that a network link can carry without fragmenting it, commonly 1500 bytes on Ethernet.Glossary · NetworkingMulticastMulticast is a method of sending a single stream of packets to a group of interested receivers instead of one copy to each recipient.Glossary · NetworkingNAT (Network Address Translation)NAT is a technique where a router rewrites IP addresses and ports in packets so many private devices can share one public IP address.Glossary · NetworkingNetwork PortA network port is a 16-bit number that identifies a specific service or connection endpoint on a host, allowing many applications to share one IP address.Glossary · NetworkingNetwork SwitchA network switch is a device that connects devices on one LAN and forwards Ethernet frames only to the port that holds the destination MAC address.Glossary · NetworkingNetwork TopologyNetwork topology is the arrangement of devices and links in a network, such as star, bus, ring or mesh, physically or logically.Glossary · NetworkingNetwork TunnelingTunneling wraps one network protocol's packets inside another protocol's packets so they can cross a network that would not otherwise carry them.Glossary · NetworkingNTP (Network Time Protocol)NTP synchronizes computer clocks over a network to within milliseconds of a reference source, using a hierarchy of time servers called strata.Glossary · NetworkingOpenVPNOpenVPN is an open-source VPN that uses TLS for key exchange and runs over UDP or TCP, with flexible, widely supported configuration.Glossary · NetworkingOSI Model (Open Systems Interconnection)The OSI model is a seven-layer conceptual framework describing how network communication works, from physical signals up to applications.Glossary · NetworkingPacket (Network Packet)A packet is a small unit of data with a header and payload that travels independently across a network, such as an IP packet.Glossary · NetworkingPacket LossPacket loss is the percentage of network packets that never reach their destination, causing retransmissions, slow transfers, choppy calls and timeouts.Glossary · NetworkingPeeringPeering is an arrangement where two networks exchange traffic directly with each other, usually without paying one another for transit.Glossary · NetworkingPingPing is a diagnostic tool that sends ICMP echo requests to a host and reports whether it replies and how long the round trip takes.Glossary · NetworkingPoE (Power over Ethernet)PoE delivers electrical power and data over a single Ethernet cable, powering devices such as IP cameras, phones and access points.Glossary · NetworkingPort ExhaustionPort exhaustion occurs when a host runs out of free ephemeral source ports for new outbound connections to a given destination.Glossary · NetworkingPort ForwardingPort forwarding is a router rule that sends incoming traffic on a chosen public port to a specific device and port inside the local network.Glossary · NetworkingPowerline AdapterA powerline adapter pair sends network data through a building's electrical wiring so Ethernet connections can reach rooms without new cabling.Glossary · NetworkingPrivate vs Public IP AddressA public IP address is reachable on the internet, while a private IP is reserved for local networks and not routed globally.Glossary · NetworkingProxy ServerA proxy server is an intermediary that forwards client requests to other servers, hiding the client, caching content or filtering traffic.Glossary · NetworkingQoS (Quality of Service)QoS is a set of techniques that prioritize certain network traffic, such as voice or video, so it gets consistent bandwidth, low delay and low loss.Glossary · NetworkingRADIUS (Remote Authentication Dial-In User Service)RADIUS is a protocol that centralizes authentication, authorization and accounting for network access such as Wi-Fi, VPN and switch ports.Glossary · NetworkingRedirect (301 vs 302)A 301 redirect marks a move as permanent and a 302 marks it as temporary; the choice affects caching, link signals and how search engines treat the old URL.Glossary · NetworkingRedirect ChainA redirect chain is a sequence of two or more redirects a request must follow before reaching its final URL.Glossary · NetworkingReverse ProxyA reverse proxy sits in front of one or more web servers, receiving client requests and forwarding them to the backend, adding TLS, caching and routing.Glossary · NetworkingRouterA router is a network device that forwards packets between different networks by reading destination IP addresses and choosing the best next hop.Glossary · NetworkingRTP (Real-time Transport Protocol)RTP is the protocol that carries real-time audio and video in numbered, timestamped packets, usually over UDP, for calls and streaming.Glossary · NetworkingRTT (Round-Trip Time)Round-trip time is how long a packet takes to travel to a destination and for its reply to return, measured in milliseconds.Glossary · NetworkingSD-WAN (Software-Defined Wide Area Network)SD-WAN is a software-managed overlay that steers traffic across multiple WAN links such as broadband, LTE and MPLS using central policies.Glossary · NetworkingServer Error (5xx)A 5xx response means the server failed to complete a valid request, so the fault lies with the server, a proxy or an upstream dependency, not the client.Glossary · NetworkingSIP (Session Initiation Protocol)SIP is a text-based signaling protocol that sets up, modifies and ends voice and video sessions over IP networks, widely used in VoIP.Glossary · NetworkingSNMP (Simple Network Management Protocol)SNMP is a protocol for polling and receiving alerts from network devices such as routers and switches about their status and counters.Glossary · NetworkingSocketA socket is the operating system endpoint for network communication, identified by an IP address, port and protocol, that programs read from and write to.Glossary · NetworkingSOCKS ProxyA SOCKS proxy is a general-purpose proxy that relays raw TCP or UDP connections for any application without interpreting the protocol inside.Glossary · NetworkingSoft 404A soft 404 is a page that tells visitors the content is missing but returns a 200 OK status, or that is so thin a search engine treats it as not found.Glossary · NetworkingSpanning Tree Protocol (STP)Spanning Tree Protocol prevents switching loops in Ethernet networks by blocking redundant links until a failure requires them.Glossary · NetworkingSplit BrainSplit brain is a failure where a network partition leaves two parts of a cluster each believing they are the primary, so both accept writes and the data diverges.Glossary · NetworkingSSID (Service Set Identifier)An SSID is the human-readable name of a Wi-Fi network that access points broadcast so devices can find and join it.Glossary · NetworkingSubnetA subnet is a logical subdivision of an IP network that groups hosts sharing the same address prefix so they can reach each other directly.Glossary · NetworkingSubnet MaskA subnet mask is a 32-bit value that tells a device which part of an IPv4 address identifies the network and which part identifies the host.Glossary · NetworkingSYN FloodA SYN flood is a denial-of-service attack that sends many TCP connection requests without completing them, exhausting a server's connection resources.Glossary · NetworkingTCP (Transmission Control Protocol)TCP is a connection-oriented transport protocol that delivers data reliably and in order between two hosts, retransmitting anything that is lost.Glossary · NetworkingTCP KeepaliveTCP keepalive sends periodic probe packets on an idle connection to check that the peer is still reachable and to stop middleboxes from dropping it.Glossary · NetworkingTelnetTelnet is an old unencrypted text protocol on TCP port 23 for remote terminal access, replaced by SSH but still used to test open ports.Glossary · NetworkingThree-Way Handshake (TCP)The three-way handshake is the SYN, SYN-ACK, ACK exchange that sets up a TCP connection and synchronizes sequence numbers on both sides.Glossary · NetworkingThroughputThroughput is the amount of data actually delivered across a network per second, which is usually lower than the link's rated bandwidth.Glossary · NetworkingTIME_WAITTIME_WAIT is a TCP connection state held by the side that closes first, keeping the socket reserved briefly to absorb late packets safely.Glossary · NetworkingTLS HandshakeThe TLS handshake is the exchange at the start of a secure connection where client and server agree on settings, verify identity and derive keys.Glossary · NetworkingTor Network (The Onion Router)Tor is a volunteer-run network that routes traffic through three encrypted relays to hide a user's IP address from the sites they visit.Glossary · NetworkingTracerouteTraceroute is a diagnostic tool that lists the routers a packet crosses on its way to a destination and the delay at each hop.Glossary · NetworkingUDP (User Datagram Protocol)UDP is a lightweight connectionless transport protocol that sends independent datagrams without handshakes, ordering or guaranteed delivery.Glossary · NetworkingUpstreamAn upstream is a server or service that sits behind a proxy or load balancer and receives the requests it forwards.Glossary · NetworkingVLAN (Virtual LAN)A VLAN is a logical network created on a switch that isolates groups of devices into separate broadcast domains regardless of physical location.Glossary · NetworkingVoIP (Voice over Internet Protocol)VoIP carries phone calls as packets over IP networks, converting speech to digital audio streams instead of using traditional circuit-switched lines.Glossary · NetworkingVPN (Virtual Private Network)A VPN creates an encrypted tunnel between your device and a VPN server, so traffic is protected in transit and appears to come from the server.Glossary · NetworkingWAN (Wide Area Network)A WAN is a network that spans large geographic distances, connecting multiple LANs across cities, countries or the whole Internet.Glossary · NetworkingWebRTC (Web Real-Time Communication)WebRTC is a set of browser APIs and protocols that enable encrypted peer-to-peer audio, video and data transfer without plugins.Glossary · NetworkingWi-FiWi-Fi is a family of wireless networking standards, based on IEEE 802.11, that lets devices join a local network over radio instead of cables.Glossary · NetworkingWi-Fi Extender (Repeater)A Wi-Fi extender receives an existing wireless signal and rebroadcasts it to widen coverage, usually at the cost of reduced throughput.Glossary · NetworkingWireGuardWireGuard is a modern, compact VPN protocol using fixed, modern cryptography and UDP, known for simple configuration and good performance.Glossary · NetworkingWPA2 vs WPA3 (Wi-Fi Protected Access)WPA2 and WPA3 are Wi-Fi security standards; WPA3 adds stronger password handshakes, protection against offline guessing and better open-network privacy.