Complete Networking Glossary A-Z

Comprehensive explanations of networking, security, and privacy terms. Each term includes context for IP diagnostics and online privacy.

Jump to: A • B • C • D • E • F • G • H • I • J • K • L • M • N • O • P • Q • R • S • T • U • V • W • X • Y • Z

A

API

Application Programming Interface – standardized way for programs to communicate. REST APIs use HTTP methods (GET, POST) to exchange data, often in JSON format.

ASN

Autonomous System Number – unique identifier for a network on the Internet. Large ISPs and hosting providers advertise routing policies via BGP using ASNs. Critical for connection type classification.

AES

Advanced Encryption Standard – symmetric encryption algorithm used in TLS, VPN protocols, and secure storage. AES-256 provides strong protection against brute force attacks.

B

Bandwidth

Maximum data transfer rate of a network connection, measured in bits per second (bps). Often confused with throughput, which is actual achieved speed.

BGP

Border Gateway Protocol – the routing protocol that connects autonomous systems across the Internet. BGP announcements determine how traffic flows between ASNs. Misconfigurations cause route leaks and hijacking.

Browser Fingerprinting

Technique to identify users by collecting browser characteristics (fonts, plugins, screen resolution). More invasive than cookies and harder to block.

C

CDN

Content Delivery Network – distributed servers caching content globally for improved performance. CDNs reduce latency and server load by serving content from nearby edge locations.

CGNAT

Carrier-Grade Network Address Translation – ISP-level NAT sharing one public IPv4 address among many customers. Makes P2P connections difficult and complicates geolocation.

Cookie

Small data file stored by websites in browsers. Session cookies expire when browser closes; persistent cookies remain until deletion. Essential for login sessions and preferences.

CSP

Content Security Policy – HTTP header preventing XSS attacks by controlling resource loading. Specifies allowed sources for scripts, styles, images, and connections.

D

DHCP

Dynamic Host Configuration Protocol – automatically assigns IP addresses, DNS servers, and network settings to devices joining a network.

DNS

Domain Name System – hierarchical lookup system translating domain names to IP addresses. DNS queries can leak real location even when using VPNs. Deep dive: What is DNS & how it works.

DNS Leak

When DNS queries bypass VPN tunnel and reveal true ISP and location. Test for leaks using our DNS Leak Test tool.

DoH

DNS over HTTPS – encrypts DNS queries using HTTPS to prevent interception and manipulation. Supported by modern browsers and resolvers like Cloudflare (1.1.1.1).

DoT

DNS over TLS – encrypts DNS queries using TLS on port 853. Alternative to DoH with similar privacy benefits but different protocol approach.

E

Encryption

Process of encoding data so only authorized parties can read it. Modern web uses AES for symmetric encryption and RSA/ECDH for key exchange in TLS.

End-to-End Encryption

Encryption where only communicating users can read messages. Prevents interception by service providers, unlike transport encryption (TLS) which only protects data in transit.

F

Firewall

Network security device filtering traffic based on predetermined rules. Can block malicious connections but may interfere with P2P applications and WebRTC.

Forward Secrecy

Cryptographic property ensuring past communications remain secure even if long-term secret keys are compromised. TLS 1.3 provides forward secrecy by default.

G

Geolocation

Process of determining geographic location from IP address. Accuracy varies significantly based on ISP data quality and VPN usage. Read: IP Geolocation Accuracy.

Gateway

Network node connecting different networks. Your router is a gateway between your home network and your ISP's network.

H

HTTPS

Hypertext Transfer Protocol Secure – HTTP encrypted with TLS. Essential for protecting sensitive data and increasingly required by browsers for security features.

HTTP/2

Major revision of HTTP supporting multiplexing, server push, and header compression. Reduces latency compared to HTTP/1.1 by eliminating head-of-line blocking.

HTTP/3

Latest HTTP version using QUIC transport protocol. Built on UDP instead of TCP, reducing connection establishment time and improving performance over unreliable networks.

Headers

Metadata sent with HTTP requests and responses. Request headers include User Agent, cookies, and accepted content types. Response headers include cache directives and security policies.

I

IP Address

Numerical label identifying a device on a network. IPv4 uses 32-bit addresses (like 192.168.1.1), IPv6 uses 128-bit addresses. Start with: What is my IP address?.

IPv4

Internet Protocol version 4 – legacy 32-bit addressing providing ~4.3 billion possible addresses. Address exhaustion drives widespread NAT usage. Compare with IPv4 vs IPv6.

IPv6

Internet Protocol version 6 – modern 128-bit addressing with virtually unlimited addresses. Enables end-to-end connectivity without NAT but adoption remains uneven. See IPv4 vs IPv6.

ISP

Internet Service Provider – company providing internet access to customers. ISPs assign IP addresses and can monitor traffic unless encrypted with VPN or HTTPS.

J

JSON

JavaScript Object Notation – lightweight data interchange format using human-readable text. Common in APIs and web applications for structured data exchange.

Jitter

Variation in latency over time. High jitter causes choppy audio/video calls and affects real-time applications. Quality of Service (QoS) can help reduce jitter.

K

Key Exchange

Cryptographic process where parties establish shared secret keys for encryption. TLS uses algorithms like ECDH (Elliptic Curve Diffie-Hellman) for secure key exchange.

L

Latency

Time delay for data to travel from source to destination, typically measured in milliseconds (ms). Affected by physical distance, network congestion, and routing. Also called RTT (Round Trip Time).

Load Balancer

Distributes incoming requests across multiple servers to prevent overload and improve reliability. CDNs often use load balancing to route users to nearest servers.

M

MAC Address

Media Access Control address – unique identifier for network interfaces. Unlike IP addresses, MAC addresses don't change and can be used for device tracking on local networks.

MTU

Maximum Transmission Unit – largest packet size that can be transmitted without fragmentation. Standard Ethernet MTU is 1500 bytes. VPNs often reduce MTU to accommodate encryption overhead.

N

NAT

Network Address Translation – technique mapping multiple private IP addresses to one public address. Enables internet access for multiple devices but complicates P2P connections and server hosting.

Network Stack

Layered model describing network communication from physical transmission (Layer 1) to applications (Layer 7). TCP/IP model includes Link, Internet (IP), Transport (TCP/UDP), and Application layers.

O

Open Source

Software with publicly available source code that can be inspected, modified, and redistributed. Provides transparency and security audibility compared to proprietary software.

OSI Model

Open Systems Interconnection model – seven-layer framework describing network communication: Physical, Data Link, Network (IP), Transport (TCP), Session, Presentation, Application.

P

Packet

Basic unit of data transmission containing headers with routing information and payload with actual data. IP packets can be fragmented if they exceed network MTU.

P2P

Peer-to-Peer – network architecture where participants share resources directly without central servers. BitTorrent, WebRTC, and blockchain networks use P2P communication.

Port

Numerical identifier for specific services on a device. Common ports include 80 (HTTP), 443 (HTTPS), 53 (DNS), 22 (SSH). Not a security boundary by itself.

Proxy

Intermediary server forwarding requests between clients and servers. Can cache content, filter requests, or hide client IP addresses. Less secure than VPNs as typically only HTTP traffic is proxied.

Q

QUIC

Transport protocol underlying HTTP/3, built on UDP instead of TCP. Reduces connection establishment time and includes encryption by default. Developed by Google, now an internet standard.

QoS

Quality of Service – network management prioritizing certain traffic types. Can reduce latency for voice/video calls and improve user experience during network congestion.

R

Router

Network device forwarding packets between networks. Home routers typically include DHCP server, firewall, and NAT functionality to connect local devices to the internet.

RTT

Round Trip Time – time for packet to travel from source to destination and back. Measures network latency and affects responsiveness of interactive applications.

S

SSL

Secure Sockets Layer – deprecated predecessor to TLS. Term still commonly used to refer to TLS connections (e.g., "SSL certificate" actually means TLS certificate).

Static IP

IP address assignment that doesn't change over time. Useful for running servers or services but more expensive than dynamic IP assignments from most ISPs. See: Static vs Dynamic IP Addresses.

Subnet

Logical subdivision of an IP network. IPv4 subnets use subnet masks (e.g., /24 = 255.255.255.0) to define network and host portions of addresses.

T

TCP

Transmission Control Protocol – reliable, ordered transport protocol used by most applications. Provides error correction and flow control but adds latency compared to UDP.

TLS

Transport Layer Security – cryptographic protocol securing communications over networks. TLS 1.3 is current standard providing confidentiality, integrity, and authenticity for HTTPS, DoH, and other protocols.

Throughput

Actual data transfer rate achieved in practice, often lower than advertised bandwidth due to protocol overhead, network congestion, and other factors.

TTL

Time to Live – field limiting packet lifetime to prevent infinite routing loops. In DNS, TTL specifies how long records can be cached before refresh is required.

U

UDP

User Datagram Protocol – lightweight transport protocol without reliability guarantees. Used for DNS, live video streaming, and QUIC. Lower latency than TCP but applications must handle packet loss.

User Agent

String identifying client software (browser, operating system, device) sent with HTTP requests. Can be used for analytics and fingerprinting. View yours with our User Agent tool.

V

VPN

Virtual Private Network – encrypted tunnel routing traffic through remote servers. Changes apparent IP address and encrypts traffic from ISP monitoring. Read: How VPNs protect you and Are free VPNs safe?.

VLAN

Virtual Local Area Network – logical network segmentation within physical infrastructure. Improves security and performance by isolating traffic types.

W

WebRTC

Web Real-Time Communication – enables peer-to-peer audio, video, and data sharing in browsers. Can leak local IP addresses even through VPNs. Test for leaks with our WebRTC Leak Test.

Wi-Fi

Wireless networking standard (IEEE 802.11) enabling devices to connect to networks over radio waves. Latest standards include Wi-Fi 6 (802.11ax) and Wi-Fi 7 (802.11be). Secure with: Secure your home Wi-Fi (2025).

WPA3

Wi-Fi Protected Access 3 – latest Wi-Fi security standard replacing WPA2. Provides stronger encryption and protection against password attacks.

X

XSS

Cross-Site Scripting – web vulnerability allowing attackers to inject malicious scripts. CSP headers help prevent XSS by controlling script execution sources.

Y

YAML

YAML Ain't Markup Language – human-readable data serialization standard. Often used for configuration files and documentation frontmatter.

Z

Zero Trust

Security model requiring verification for every user and device, regardless of location. Assumes no inherent trust and continuously validates access requests.

Zone File

DNS database containing records for a domain. Includes A records (IPv4), AAAA records (IPv6), MX records (email), and other resource records.

Cross-Reference Guide:

Missing a term? Email admin@checkmyipaddress.xyz.