Networking glossary

The older Wi-Fi band — longer range and better wall penetration, but slower and crowded with non-Wi-Fi interference.

The fourth generation of cellular networks — the baseline standard for most mobile data globally.

The mid-band Wi-Fi spectrum — much faster than 2.4 GHz with less interference, but shorter range.

The fifth generation of cellular networks, with peak speeds in the gigabits and much lower latency than 4G.

The newest Wi-Fi spectrum (Wi-Fi 6E/7), uncrowded and high-capacity but limited to current-generation devices.

DNS record mapping a domain name to an IPv4 address.

DNS record mapping a domain name to an IPv6 address.

A device that bridges Wi-Fi clients onto a wired network. Often integrated into home routers.

A routing technique where one IP address is announced from many locations and traffic naturally reaches the nearest one. Used by CDNs and public DNS.

An internet link with different upload and download speeds — typical of cable, DSL, and fixed wireless.

DNS servers that own the actual records for a domain and respond to recursive resolver queries.

A collection of IP networks under one operator's control, with a globally unique ASN, that exchanges routing with other ASes via BGP.

The link between mesh nodes (or between a tower and the core). Dedicated wireless or wired backhaul drastically improves mesh performance.

The maximum amount of data that can be transmitted over a network link in a given period, typically measured in megabits per second (Mbps) or gigabits per second (Gbps).

A Wi-Fi technique that focuses signal toward a specific device rather than broadcasting equally in all directions.

Border Gateway Protocol — the protocol that announces and chooses routes between autonomous systems on the internet.

A router setting that disables NAT/DHCP/Wi-Fi so the device acts as a pure modem and hands the public IP to a downstream router.

Any always-on internet connection that exceeds a regulatory minimum speed — historically meant to distinguish modern access from dial-up.

Excessive buffering in network equipment that causes latency spikes under load. Mitigated by SQM algorithms like CAKE and fq_codel.

A measurement that loads the link and observes how much latency rises — exposing inadequate queue management.

Common Applications Kept Enhanced — an advanced SQM algorithm that automatically tunes itself and handles cable/DSL overhead correctly.

Ethernet cable rated for 1 Gbps over up to 100 meters.

Ethernet cable rated for 10 Gbps over up to 55 meters and 1 Gbps over longer runs.

Improved Cat6 supporting 10 Gbps over the full 100-meter run.

A Content Delivery Network — a globally distributed set of edge servers that cache content close to users to reduce latency and offload origin servers.

An organization trusted by browsers to issue TLS certificates that authenticate website identities.

Carrier-Grade NAT — ISPs sharing a single public IPv4 across many customers. Common on mobile and many ISPs facing IPv4 exhaustion.

How wide a Wi-Fi channel is (20, 40, 80, 160, 320 MHz). Wider channels are faster but more interference-prone.

Classless Inter-Domain Routing — a notation (like 10.0.0.0/8) for IP ranges that replaced fixed network classes.

Canonical Name record — points one domain at another, useful for aliasing.

A monthly limit on total data usage. Exceeding it may trigger throttling, overage charges, or a soft cap.

Dynamic DNS — keeps a domain name pointed at a changing IP, used by self-hosters on residential connections.

Distributed Denial of Service — an attack that overwhelms a target with traffic from many sources.

Dynamic Host Configuration Protocol — assigns IP addresses, gateways, and DNS servers automatically when a device joins a network.

The Domain Name System — the internet's address book, translating human-readable domain names into the IP addresses computers use to route traffic.

A server that handles DNS lookups on behalf of a client — walking the global DNS hierarchy and returning the IP address for a queried domain.

DNS Security Extensions — cryptographically signs DNS records so resolvers can verify they weren't tampered with.

The standard for cable internet over coaxial lines. DOCSIS 3.1 supports multi-gigabit downloads; 4.0 brings symmetric multi-gigabit.

DNS over HTTPS — encrypts DNS lookups inside an HTTPS connection, preventing on-path observers from seeing or tampering with queries.

DNS over TLS — encrypts DNS lookups using TLS on port 853.

The rate at which data can be received from the internet by your device, typically expressed in megabits per second (Mbps).

Digital Subscriber Line — internet over copper phone lines. Speeds depend on distance from the exchange.

An IP address assigned automatically (usually via DHCP) that may change over time.

The dominant wired LAN technology, defined by IEEE 802.3. Speeds today range from 100 Mbps to 100 Gbps.

Automatically switching to a backup system or link when the primary fails.

Internet service delivered over fiber-optic cables that transmit data as pulses of light, offering symmetric multi-gigabit speeds and very low latency.

A device or software that filters traffic by rule, blocking or allowing connections based on source, destination, and port.

Home internet delivered over cellular or proprietary wireless links to a fixed antenna at the customer site.

A queue-management algorithm that fairly shares bandwidth across flows and keeps latency low under load.

The network device that connects a local network to other networks — most commonly your home router acting as the bridge between your LAN and the internet.

Mapping IP addresses to approximate geographic locations using commercial databases.

Traditional satellite internet from satellites 36,000 km up — high latency (~600 ms) makes it poor for interactive use.

Each router a packet traverses between source and destination.

The third major version of HTTP, built on QUIC/UDP. Designed for lower latency and resilience to packet loss.

HTTP secured by TLS. Encrypts traffic between browser and server and authenticates the server's identity.

Interactive Connectivity Establishment — the framework that tries STUN, TURN, and direct paths to set up peer connections.

Internet Control Message Protocol — the lightweight protocol behind ping and traceroute, used for network diagnostics and error messages between routers and hosts.

Internet Protocol version 4 — the original 32-bit addressing scheme used to identify devices on the internet, written as four decimal numbers like 192.168.1.1.

Internet Protocol version 6 — the successor to IPv4 that uses 128-bit addresses, providing a practically unlimited address space written in hexadecimal.

An Internet Service Provider — the company that connects your home or business to the public internet over fiber, cable, DSL, fixed wireless, or cellular.

Internet Exchange Point — a physical facility where many networks meet to peer.

The variation in latency between successive packets, measured in milliseconds — a key indicator of network stability.

Local Area Network — the network inside a single home, office, or campus.

The round-trip time, measured in milliseconds, for a packet of data to travel from your device to a server and back.

A device or service that distributes traffic across multiple backend servers.

The hostname for the loopback interface — usually resolves to 127.0.0.1.

The local-only address (127.0.0.1 / ::1) that always refers to the local machine.

A 48-bit hardware identifier burned into every network interface. Used to address devices on the local link layer (Layer 2).

Maximum Bitrate — a per-flow cap applied by carriers, sometimes used to throttle specific traffic types.

A wireless system that uses multiple cooperating nodes to blanket a home in Wi-Fi, seamlessly handing off devices between nodes as you move.

A device that translates between your ISP's transmission medium (fiber, cable, DSL) and standard Ethernet that your router and devices understand.

Mean Opinion Score — a 1–5 quality rating for voice calls, derived from latency, jitter, and loss measurements.

Maximum Transmission Unit — the largest packet size a network link can carry without fragmentation. Default for Ethernet is 1500 bytes.

Multi-User MIMO — lets a router transmit to multiple devices simultaneously using multiple antennas.

Mail Exchange record — tells email servers where to deliver mail for a domain.

Network Address Translation — lets many devices share one public IP by rewriting addresses and ports as packets cross the router.

The slowdown that occurs when more traffic is offered to a network link than the link can carry, causing queueing, latency spikes, and packet loss.

Wi-Fi 6 multi-user efficiency feature that lets a router talk to many devices in the same time slot, improving performance in crowded networks.

Optical Network Terminal — converts a fiber-optic signal into Ethernet for your home router.

The fundamental unit of data on an IP network — a small, self-contained block carrying source, destination, and a piece of the payload.

The percentage of network packets that fail to arrive at their destination, expressed as a percent of packets sent.

A short Ethernet cable used to connect devices to switches or patch panels.

An arrangement where two networks exchange traffic directly, usually without payment, to reduce latency and transit costs.

A network utility (and the metric it reports) that measures the round-trip time for a small ICMP packet between two hosts.

Power over Ethernet — delivers power and data over a single Ethernet cable, common for access points and IP cameras.

A 16-bit number identifying a specific service on a host. HTTPS uses 443, SSH uses 22, DNS uses 53.

A router rule that exposes a specific local service to the internet by mapping a public port to an internal address.

Address ranges (10.x, 172.16–31.x, 192.168.x) reserved for local networks and never routed on the public internet.

DNS resolvers operated by third parties (Cloudflare, Google, Quad9, OpenDNS) and offered free of charge as alternatives to your ISP's resolver.

An IP address that is routable on the public internet, typically assigned to a home router by the ISP.

Quality of Service — a set of router techniques that prioritize latency-sensitive traffic (games, calls) over bulk traffic (downloads, backups) to keep responsiveness high under load.

A UDP-based transport protocol designed by Google and now standardized. Underpins HTTP/3.

A DNS server that walks the global hierarchy on behalf of clients and caches answers — same as a resolver.

Looking up the hostname associated with an IP address, used in email authentication and logging.

A server that forwards client requests to one or more backend servers, often providing TLS, caching, and load balancing.

When a Wi-Fi client moves between access points without dropping the connection. Mesh systems improve roaming behavior.

The total time for a packet to travel to a destination and the response to return. Reported by ping; same as latency.

A network device that forwards data between networks — most commonly the box in your home that joins your local devices to your ISP's network.

Real-Time Streaming Protocol — used for controlling streaming media servers.

Service-Level Agreement — a contractual commitment to specific uptime, latency, or response targets.

Server Name Indication — a TLS extension that lets one IP host multiple HTTPS sites by including the hostname in the handshake.

A measurement that estimates a connection's download bandwidth, upload bandwidth, and latency by transferring known amounts of data to and from a nearby test server.

Smart Queue Management — modern queue-management algorithms (fq_codel, CAKE) that eliminate bufferbloat with minimal configuration.

Service Set Identifier — the human-readable name of a Wi-Fi network broadcast by your router.

The predecessor to TLS, now deprecated. The term 'SSL certificate' is still widely used for what is technically a TLS certificate.

SpaceX's low-earth-orbit satellite internet system, offering lower latency than geostationary satellite.

An IP address manually assigned and unchanging — common for servers.

A protocol that helps a device behind NAT learn its public IP and port, used in WebRTC and VoIP.

A subdivided portion of an IP network, defined by a prefix length like /24.

A network device that forwards traffic between devices on the same LAN using MAC addresses.

An internet link with equal upload and download speeds — typical of fiber.

Transmission Control Protocol — the connection-oriented, reliable transport protocol that underpins most web and email traffic on the internet.

Intentional rate-limiting by an ISP or service, often after a usage threshold or for specific applications.

The actual sustained rate of data delivered across a network link, measured over a window of time — distinct from the link's theoretical bandwidth.

Transport Layer Security — the protocol that encrypts HTTPS, modern SMTP, and most secure internet traffic.

The negotiation at the start of an HTTPS session that exchanges keys, validates certificates, and establishes the encrypted channel.

A diagnostic that maps the sequence of routers (hops) a packet traverses to reach a destination, along with the latency to each hop.

A paid arrangement where one ISP carries another's traffic to the rest of the internet.

Time To Live — how long a DNS record may be cached before being re-fetched. Lower TTLs let changes propagate faster but increase lookup volume.

A relay protocol for traversing strict NATs when direct connections fail — used as a fallback in WebRTC.

Arbitrary text DNS record, used for SPF, DKIM, DMARC, domain verification, and similar metadata.

User Datagram Protocol — a lightweight, connectionless transport protocol used where low latency matters more than guaranteed delivery, including games, voice, video, and DNS.

The rate at which data can be sent from your device to the internet, typically expressed in megabits per second (Mbps).

The percentage of time a service is reachable and healthy. '99.9%' uptime allows roughly 8.7 hours of downtime per year.

Virtual LAN — logically segments one physical network into isolated broadcast domains.

A Virtual Private Network — an encrypted tunnel between your device and a remote server that hides your traffic from local networks and changes your apparent location.

Wide Area Network — any network spanning more than a single site. From a home perspective, the WAN side of a router faces the ISP.

A browser-native standard for real-time audio, video, and data — powers most browser-based calling and conferencing.

A family of wireless networking standards (IEEE 802.11) that connect devices to a local network using radio waves in the 2.4, 5, and 6 GHz bands.

Connecting mesh nodes via Ethernet instead of relying on a wireless inter-node link. Usually doubles edge performance.

The current Wi-Fi security standard, replacing WPA2 with stronger key exchange and protection against offline attacks.