Networking Glossary
Plain-English definitions for every internet and networking term you'll encounter — from Mbps and latency to DOCSIS and bufferbloat.
Speed
Mbps
The standard unit for measuring internet connection speed.
Gbps
1 Gbps = 1000 Mbps — the speed tier of modern fiber plans.
Bandwidth
The maximum amount of data that can flow through a connection at once — the pipe width, not the water speed.
Download Speed
How fast your connection pulls data from the internet to your device.
Upload Speed
How fast your device sends data to the internet — the metric that matters for video calls, live streaming, and cloud backup.
Throughput
The actual data transfer rate measured under real conditions — what a speed test measures.
Bitrate
Bitrate: The number of bits transmitted or processed per second — the fundamental measure of data throughput for streaming, downloads, and network connections…
Performance
Latency
The time it takes for data to travel from your device to a server and back.
Ping
The round-trip time in milliseconds between your device and a server — the gaming metric that matters most.
RTT
Round-Trip Time — total time for a packet to travel from sender to destination and back.
Jitter
The variation in ping over time — the metric that breaks video calls and causes lag spikes.
Packet Loss
The percentage of data packets that fail to reach their destination — the most damaging network metric for real-time applications.
Bufferbloat
Excessive latency caused by your router queueing too many packets — the hidden cause of lag during downloads.
QoS (Quality of Service)
QoS is a router feature that prioritises specific types of network traffic to ensure latency-sensitive applications get bandwidth before background tasks.
SQM (Smart Queue Management)
SQM is an advanced router feature that prevents bufferbloat by actively managing queue depth, keeping latency low even when the connection is fully saturated.
Connection Types
Symmetric Speed
A connection where upload speed equals download speed — the defining advantage of fiber over cable.
Fiber Internet
Internet delivered over glass fibre cables — the fastest, most reliable residential broadband technology.
Cable Internet
Broadband delivered over coaxial cable TV infrastructure — fast download, limited upload, shared with neighbours.
5G
5G is the fifth generation of cellular wireless technology, offering peak speeds of 1–10 Gbps and low latency — used for both mobile data and as a home internet alternative via fixed wireless access.
DSL
DSL (Digital Subscriber Line): Broadband internet delivered over existing copper telephone lines. Plain-English definition covering ADSL, VDSL, and how DSL…
GPON
GPON (Gigabit Passive Optical Network): A fiber-optic access technology that shares a single fiber strand among multiple premises using passive optical…
LEO Satellite
LEO Satellite (Low Earth Orbit): Satellites at 550–1,200 km altitude used by Starlink and similar services to deliver broadband with much lower latency than…
XGS-PON
XGS-PON: A 10 Gbps symmetric passive optical network standard used by ISPs to deliver multi-gigabit fibre broadband — how it differs from GPON and why it…
Infrastructure
DNS
The internet's phonebook — translates domain names like google.com into IP addresses.
IP Address
A unique numerical label assigned to every device on a network — your internet identity.
NAT
How your router lets multiple devices share a single public IP address.
DOCSIS
The protocol that runs broadband internet over cable TV coaxial cable infrastructure.
IPv6
The successor to IPv4 — provides vastly more IP addresses and eliminates the need for NAT.
ISP
The company that provides your internet connection — Xfinity, AT&T, Spectrum, and similar.
CGNAT (Carrier-Grade NAT)
CGNAT is a technique where your ISP shares a single public IP address across multiple customers, which prevents direct port forwarding and can affect gaming and self-hosting.
VPN (Virtual Private Network)
A VPN encrypts your internet traffic and routes it through a remote server, masking your IP address and preventing your ISP from seeing your activity.
DHCP (Dynamic Host Configuration Protocol)
DHCP is the protocol that automatically assigns IP addresses to devices on a network. Your router runs a DHCP server that hands out addresses when devices connect.
ASN
ASN (Autonomous System Number): A unique identifier assigned to each network on the internet that controls its own routing policy. Plain-English definition.
CDN
CDN (Content Delivery Network): A network of servers that caches content close to users to reduce latency and load times. Plain-English definition with…
CIDR
CIDR (Classless Inter-Domain Routing): A compact notation for expressing IP address ranges and subnet sizes, such as 192.168.1.0/24. Plain-English definition…
CNAME
CNAME (Canonical Name): A DNS record type that aliases one domain name to another, allowing multiple hostnames to point to the same destination. Plain-English…
Default Gateway
Default Gateway: The router IP address that your device sends traffic to when the destination is outside your local network. Plain-English definition with…
Edge Computing
Edge Computing: Processing data close to where it is generated rather than sending it to a distant cloud data center, reducing latency for real-time…
FQDN
FQDN (Fully Qualified Domain Name): The complete, unambiguous domain name specifying a host's exact location in the DNS hierarchy. Plain-English definition…
Gateway
Gateway: A network node that connects two different networks and translates between their protocols — the bridge between your local network and the internet…
IPv4
IPv4 (Internet Protocol version 4): The original 32-bit IP addressing system that powers most internet traffic, providing about 4.3 billion addresses…
Kernel Network Stack
Kernel Network Stack: The OS kernel subsystem that processes network packets — implementing TCP/IP, routing, firewall rules, and socket APIs. How the Linux…
LAN
LAN (Local Area Network): A network connecting devices within a limited area — your home, office, or building — as opposed to the WAN that connects to the…
Loopback
Loopback: The special IP address 127.0.0.1 (or ::1 in IPv6) that routes traffic back to the local machine itself — used for testing and local network services…
MPLS
MPLS (Multiprotocol Label Switching): A high-performance routing technique that forwards packets using short labels instead of long IP addresses, enabling…
Multicast
Multicast: A one-to-many IP delivery method where a single packet is sent to a group address and routers duplicate it only where needed — used for IPTV, live…
Netmask
Netmask (Subnet Mask): A 32-bit number that divides an IP address into network and host portions, telling your device which addresses are local vs. which…
Network Tunnel
Network Tunnel: A method of encapsulating one network protocol inside another to carry traffic across incompatible networks or create encrypted private paths …
Port
Port: A 16-bit number that identifies a specific process or service within a networked device — allowing multiple services to share one IP address…
Private IP
Private IP Address: An IP address from RFC 1918 reserved ranges (10.x.x.x, 172.16–31.x.x, 192.168.x.x) used within local networks and not routed on the public…
Proxy
Proxy Server: An intermediary server that forwards requests between clients and destination servers — used for caching, filtering, anonymity, and bypassing…
Public IP
Public IP Address: A globally unique IP address assigned by your ISP that identifies your network on the internet. Every connection you make to a website…
Subnet
Subnet: A logical subdivision of an IP network, defined by a network address and subnet mask, that groups devices into isolated segments to improve security…
TLD
TLD (Top-Level Domain): The last segment of a domain name — .com, .org, .net, .uk — managed by ICANN and delegated to registry operators. Plain-English…
URL
URL (Uniform Resource Locator): The complete address of a resource on the web — scheme, host, port, path, query string, and fragment. How browsers parse URLs…
VLAN
VLAN (Virtual LAN): A logical network segment created on a managed switch that isolates broadcast domains without requiring separate physical hardware — used…
VPS
VPS (Virtual Private Server): A virtualized server environment running on shared physical hardware — giving dedicated CPU, RAM, and storage resources with root…
WAN
WAN (Wide Area Network): A network that spans a large geographic area — connecting homes and offices to the internet, or linking branch offices across cities…
WHOIS
WHOIS: A query protocol that returns registration information about domain names and IP addresses — registrant contact details, registrar, registration dates…
Hardware
Router
The device that connects your home network to the internet and routes traffic between your devices.
Modem
The device that connects your home to the ISP's network by converting their signal into Ethernet.
ONT
Optical Network Terminal — converts the fiber signal into Ethernet. The fiber equivalent of a modem.
Wi-Fi
Wireless local area networking — the radio link between your devices and router.
Ethernet
Wired network connection via cable — faster, more reliable, and lower latency than Wi-Fi.
SSID (Wi-Fi Network Name)
An SSID is the visible name of a Wi-Fi network. Devices use the SSID to identify and connect to a specific wireless network.
Wi-Fi 6 (802.11ax)
Wi-Fi 6 is the sixth generation of Wi-Fi, offering higher speeds, better performance in dense device environments, and improved battery efficiency through OFDMA and TWT.
MAC Address
MAC Address (Media Access Control): A unique hardware identifier burned into every network interface card. Plain-English definition with examples.
NAS
NAS (Network Attached Storage): A dedicated file server connected to your network that provides shared storage accessible by all devices — without needing a…
NIC
NIC (Network Interface Card): The hardware component that connects a computer to a network — handling Ethernet or Wi-Fi at the physical layer. Plain-English…
PHY
PHY (Physical Layer): The lowest layer of the OSI model responsible for transmitting raw bits over a physical medium — cable, fibre, or radio. Also refers to…
PoE
PoE (Power over Ethernet): A standard that delivers electrical power alongside data over standard Ethernet cables — eliminating the need for separate power…
QAM
QAM (Quadrature Amplitude Modulation): A modulation technique that encodes multiple bits per symbol by varying both signal amplitude and phase — used in Wi-Fi…
RJ45
RJ45: The 8-pin modular connector used for Ethernet networking — the rectangular plug at the end of every network cable. Plain-English definition including…
Server
Server: A computer or software process that provides services, data, or resources to other computers (clients) over a network — from web servers to DNS servers…
SFP
SFP (Small Form-factor Pluggable): A hot-swappable transceiver module that plugs into a switch or router to provide fibre optic or copper connectivity — used…
Switch
Network Switch: A Layer 2 device that connects multiple devices on a LAN and forwards Ethernet frames only to the correct destination port using MAC address…
Trunk Port
Trunk Port: A switch port configured to carry traffic from multiple VLANs simultaneously using 802.1Q VLAN tagging — connecting switches to each other or to…
Diagnostics
Network Architecture
Static IP
A permanently-assigned IP address — required for hosting services that must be reachable at a stable address.
Reverse Proxy
A server in front of backend applications that handles TLS, load balancing, caching, and security.
Email Authentication
MX Record
DNS record specifying which mail server is responsible for receiving email for a domain.
SPF
Sender Policy Framework — lists IPs authorized to send mail for a domain.
DKIM
DomainKeys Identified Mail — cryptographic signature on outgoing email.
DMARC
Policy that ties SPF and DKIM to the visible From: domain.
Smart Home
Additional Network Terms
BGP
The Border Gateway Protocol that lets autonomous systems announce routes across the global internet.
Firewall
A filtering system that allows or blocks network traffic based on rules, state, applications, or identity.
Fiber
Glass or plastic strands that carry data as light, powering modern long-haul and last-mile broadband.
MQTT
A lightweight publish/subscribe messaging protocol commonly used by IoT and smart home devices.
IGMP
The protocol IPv4 hosts use to join and leave multicast groups on local networks.
SMB
The file and printer sharing protocol used by Windows, NAS appliances, and many home servers.
API
API (Application Programming Interface): A defined contract that lets one piece of software request data or services from another. Plain-English definition…
Cache
Cache: A temporary store of data kept close to where it is needed to reduce fetch time. Plain-English definition covering DNS cache, browser cache, and CDN…
Half-Duplex
Half-Duplex: A communication mode where data flows in both directions but only one direction at a time — like a walkie-talkie. Plain-English definition versus…
IoT
IoT (Internet of Things): The network of physical devices — thermostats, cameras, appliances — that connect to the internet to send and receive data…
Network Topology
Network Topology: The physical or logical arrangement of devices and connections in a network — star, bus, ring, mesh, and hybrid. How topology affects…
Packet
Packet: A small unit of data sent across a network, containing a header with routing information and a payload with the actual content. All internet traffic…
Wireless
WiFi 6E
Extension of WiFi 6 into the 6 GHz band — more spectrum, less congestion.
WiFi 7
Seventh-generation WiFi with 320 MHz channels, Multi-Link Operation, and 4K QAM.
Captive Portal
Sign-in page presented before guest WiFi access — common at hotels, airports, cafes.
Backhaul
Backhaul: The high-capacity link that connects a local network or access point back to the core internet infrastructure. Plain-English definition with examples.
BSSID
BSSID (Basic Service Set Identifier): The MAC address of a Wi-Fi access point's radio, uniquely identifying each wireless network in the area. Plain-English…
Mesh Network
Mesh Network: A Wi-Fi system where multiple nodes communicate with each other to extend coverage, eliminating dead zones without separate SSIDs or manual…
MIMO
MIMO (Multiple-Input Multiple-Output): A Wi-Fi antenna technology that uses multiple antennas to transmit and receive data simultaneously, increasing…
OFDMA
OFDMA (Orthogonal Frequency Division Multiple Access): A Wi-Fi 6 technology that divides a channel into sub-channels called resource units, letting a router…
Protocols
NTP
Network Time Protocol — synchronizes clocks across the internet to within milliseconds.
VoIP
Voice over IP — phone calls transmitted as digital packets over IP networks.
ARP
ARP (Address Resolution Protocol): The protocol that maps IP addresses to MAC addresses on a local network. Plain-English definition with examples.
DSCP
DSCP (Differentiated Services Code Point): A 6-bit field in IP packet headers used to classify and prioritize traffic for Quality of Service. Plain-English…
FTP
FTP (File Transfer Protocol): A standard network protocol for transferring files between a client and server over TCP. Plain-English definition covering FTP…
HSTS
HSTS (HTTP Strict Transport Security): A web security policy that forces browsers to only connect to a site over HTTPS, preventing downgrade attacks…
HTTP
HTTP (Hypertext Transfer Protocol): The foundation protocol of the web that defines how browsers request and receive web pages from servers. Plain-English…
HTTPS
HTTPS (HTTP Secure): HTTP with TLS encryption added — securing web traffic so only the browser and server can read it. Plain-English definition with how it…
ICMP
ICMP (Internet Control Message Protocol): The diagnostic protocol used by ping and traceroute to report network errors and test connectivity. Plain-English…
IMAP
IMAP (Internet Message Access Protocol): The protocol that lets email clients access and sync messages stored on a mail server. Plain-English definition versus…
MTU
MTU (Maximum Transmission Unit): The largest packet size a network interface can transmit in a single frame. Understanding MTU prevents fragmentation, black…
POP3
POP3 (Post Office Protocol 3): An email retrieval protocol that downloads messages from a mail server to your device and typically deletes them from the…
QUIC
QUIC: A modern transport protocol built on UDP that provides encrypted, multiplexed connections with faster handshakes than TCP+TLS — the foundation of HTTP/3…
SMTP
SMTP (Simple Mail Transfer Protocol): The standard protocol for sending and relaying email between mail servers and from email clients to outgoing mail…
SNI
SNI (Server Name Indication): A TLS extension that tells a server which hostname the client is connecting to, enabling one IP address to host multiple HTTPS…
SOCKS
SOCKS (SOCKS5): A proxy protocol that routes any TCP or UDP traffic through an intermediary server — more versatile than HTTP proxies as it works with any…
SSH
SSH (Secure Shell): An encrypted network protocol for remote login, command execution, file transfer, and port forwarding — the standard way to securely…
TCP
TCP (Transmission Control Protocol): The connection-oriented protocol that guarantees ordered, reliable delivery of data over the internet. Plain-English…
TTL
TTL (Time to Live): A counter in IP packets that decrements at each router hop, preventing packets from looping forever — and a DNS cache duration that…
UDP
UDP (User Datagram Protocol): A connectionless transport protocol that sends packets without guaranteeing delivery or order — used for gaming, video calls, and…
UPnP
UPnP (Universal Plug and Play): A network protocol that lets devices automatically discover each other and open router port mappings without manual…
Security
DoH
DNS over HTTPS — encrypts DNS queries so ISPs cannot see which sites you visit.
DNSSEC
DNS Security Extensions — cryptographically signs DNS records to prevent tampering.
mTLS
Mutual TLS — both server AND client authenticate with certificates.
DMZ
Demilitarized Zone — network segment between trusted and untrusted networks.
Port Forwarding
Maps a public port to a specific internal device through NAT.
DDoS
DDoS (Distributed Denial of Service): A flood of traffic from thousands of sources that overwhelms a server or connection, making it unavailable. Plain-English…
Encryption
Encryption: The process of encoding data so only authorized parties can read it. Plain-English definition covering symmetric, asymmetric, TLS, and Wi-Fi…
TLS
TLS (Transport Layer Security): The cryptographic protocol that secures HTTPS, email, and nearly every modern internet connection — encrypting data in transit…
WEP
WEP (Wired Equivalent Privacy): The original Wi-Fi security protocol from 1997, now completely broken and deprecated. Why WEP is insecure, how it was cracked…
WPA
WPA (Wi-Fi Protected Access): The 2003 interim replacement for broken WEP, using TKIP encryption as a stopgap until WPA2. Why WPA is deprecated and should be…
WPA2
WPA2 (Wi-Fi Protected Access 2): The 2004 Wi-Fi security standard using AES-CCMP encryption — the current baseline for secure Wi-Fi. How WPA2 works, KRACK…
WPA3
WPA3 (Wi-Fi Protected Access 3): The 2018 Wi-Fi security standard adding SAE handshake, forward secrecy, and OWE encrypted open networks over WPA2. What WPA3…
WPS
WPS (Wi-Fi Protected Setup): A 2006 standard for simplified Wi-Fi device pairing via PIN or push-button. Why the WPS PIN method has a critical vulnerability…
DNS Records
A Record
The fundamental DNS record mapping a hostname to an IPv4 address.
AAAA Record
The IPv6 counterpart of the A record — maps a name to a 128-bit address.
TXT Record
Arbitrary text in DNS — the home of SPF, DKIM, DMARC, and domain verification.
PTR Record
Reverse DNS — maps an IP address back to a hostname, vital for mail.
SRV Record
Locates the host and port for a service, with priority and weight.
Anycast
One IP served from many locations, routing each user to the nearest.
DNS Propagation
Why a DNS change takes time to be visible everywhere — it's all TTL.
Broadband & ISP
Data Cap
A monthly limit on how much data your plan allows before fees or throttling.
Bandwidth Throttling
The deliberate slowing of a connection by an ISP — and how to detect it.
Network Congestion
When demand exceeds capacity — the cause of peak-hour slowdowns.
Last Mile
The final stretch of network to your home — the usual bottleneck.
Peering
Networks interconnecting directly to exchange traffic, often free.
IP Transit
Paying a provider to carry your traffic to the whole internet.
Net Neutrality
The principle that ISPs should treat all internet traffic equally.
Wi-Fi Signal & Coverage
Access Point
The device that broadcasts Wi-Fi and bridges clients to a wired network.
Bridge Mode
Disabling routing so another device handles it — the cure for double NAT.
Band Steering
Guiding devices to the best Wi-Fi band under one network name.
Beamforming
Focusing the Wi-Fi signal toward each device for better range.
Wi-Fi Roaming
Moving between access points without dropping the connection.
RSSI
The measured strength of a received Wi-Fi signal, in dBm.
dBm
The logarithmic unit for signal power — closer to zero is stronger.
SNR
Signal-to-noise ratio — often a better speed predictor than strength.
Channel Width
How much spectrum a channel uses — 20 to 160 MHz, speed vs reliability.
Dual-Band & Tri-Band
How many Wi-Fi bands a router runs at once, and when it matters.
Devices & Connectivity
Hotspot
A Wi-Fi access point that shares an internet connection.
Tethering
Sharing one device's internet with another over Wi-Fi, USB, or Bluetooth.
Wi-Fi Extender
Rebroadcasts an existing signal to reach dead zones, at a speed cost.
Powerline
Carries network data over your home's electrical wiring.
MoCA
Runs Ethernet over coaxial TV cabling — fast and stable.
Firmware
The built-in software that runs your router — keep it updated.
Streaming & Transport
Codec
Compresses audio and video so it can stream over the internet.
Buffering
Pre-loading media for smooth playback — and the wheel when it fails.
Three-Way Handshake
How TCP establishes a connection before sending data.
Unicast
One-to-one delivery — the default for almost all internet traffic.
Network Models & Fundamentals
OSI Model
The seven-layer framework for how networks move data.
TCP/IP Model
The four-layer model the internet actually runs on.
Latency vs Throughput
Delay versus data rate — why bandwidth alone isn't speed.
MSS
The largest data payload TCP puts in one segment.
Jumbo Frames
Oversized Ethernet frames that cut overhead on fast LANs.
Congestion Control
How TCP finds the right speed without overwhelming the network.
VPN & Modern Security
WireGuard
The fast, lightweight, modern VPN protocol.
OpenVPN
The mature, configurable VPN protocol with a firewall-friendly TCP mode.
IPsec
Standards-based encryption at the IP layer for site-to-site and mobile VPNs.
DNS over TLS
Encrypted DNS on a dedicated port — the companion to DoH.
Pi-hole
Network-wide ad and tracker blocking at the DNS level.
Encrypted Client Hello
Hides the website name in the TLS handshake, closing the SNI leak.
Zero Trust
Never trust, always verify — the modern access-security model.
SD-WAN
Software-defined steering of business traffic across many links.