Glossary

IPv6 privacy extensions are a feature designed to protect user privacy by preventing long-term tracking of devices based on their IPv6 address. Devices can automatically generate their own IPv6 addresses…

A blacklist is a list of IP addresses, domains, or email servers that have been flagged as sources of spam, malicious activity, or other harmful behavior. When an IP address…

A closed port is a network port that exists on a device, but where no application or service is listening, so incoming connection attempts are rejected. Every device on a…

When one side of a network connection abruptly terminates that connection, that’s called a connection reset. Instead of closing through the normal connection, the reset signal ends the connection immediately. …

A connection timeout occurs when a device attempts to communicate with a server or another device but does not receive a response within an expected time window. Rather than waiting…

When you connect to the internet through a home or mobile connection, your IP address is assigned by an ISP that serves individual customers. A datacenter IP, on the other…

A dedicated IP is an IP address assigned exclusively to a single user, account, or server. Unlike a shared IP, which is used by many different users simultaneously, a dedicated…

A DNS cache is a small memory storage that keeps track of recently visited domain names and their IP addresses, so your device doesn’t have to look them up again…

A DNS resolver is a server that translates human-readable domain names into the IP address computers use to communicate. When you type a website address into your browser, the resolver…

Every website has at least one IP address, a string of numbers that tells your device where to find that site. A DNS server translates the human-readable domain name you…

A dynamic IP address is an IP address that changes over time rather than staying fixed. Most internet users have one. When you connect to the internet, your ISP assigns…

A filtered port is a network port that cannot be properly checked because something is blocking access to it. Usually, a firewall, router, or security system is blocking the probe,…

When you need a security system to monitor and filter the traffic moving in and out of a network, you need a firewall. These security structures work by applying specific…

A forward DNS lookup (also called forward DNS resolution) is the standard process the internet uses to connect you to websites. DNS stands for Domain Name System. It converts domain…

A forward proxy is a server that sits between a user’s device and the internet, routing outbound requests on the client’s behalf. Rather than connecting directly to a destination, the…

A gateway is a network node that serves as an entry and exit point between two different networks. Most commonly, it’s the device in your home or office (typically your…

A hop is a single step in the journey data takes across the internet. When you send a request from your device, that data rarely travels directly to its destination.…

If you’ve heard of a MAC address and thought it was about Apple devices or macOS, you’re not alone. Plenty of people make that assumption. However, a MAC address has…

A network interface is the point where a device connects to a network. It’s the hardware or software component that allows data to move in and out. Every device that…

Every time you load a webpage or send a request online, your data moves through a series of intermediate points, including routers, switches, and servers. That sequence of steps is…

Have you ever watched a download bar fill up in chunks, or seen a webpage load image by image? You’re seeing packets at work. When data travels across the internet,…

A port is a numerical label used by a device’s operating system to direct incoming and outgoing network traffic to the right application or service. While an IP address identifies…

A private IP address is a numerical label assigned to a device within a local network, such as a home or office setup. Unlike a public IP address, which is…

A protocol is a set of rules that controls how data is sent and received over a network. Every device connected to the internet follows these rules so that different…

A proxy server is an intermediary server (AKA: a computer) that functions between your device and the internet. When you send a request through a proxy, that request goes to…

A public IP address is the address assigned to your network by your internet service provider that identifies it on the open internet. It’s the address websites, apps, and online…

A regional IP, sometimes called a region-specific IP address, is an IP address associated with a particular geographic region. Every IP is allocated through organizations like the Internet Assigned Numbers…

Your home internet connection comes with an IP address that is assigned by your Internet Service Provider (ISP). When this IP address comes from a consumer ISP and is tied…

A reverse proxy server sits in front of one or more web servers and intercepts incoming requests from users before those requests ever reach the actual server. To the user,…

A router is a networking device that directs data traffic between your home or office network and the internet. When you send a request online, such as loading a webpage…

A session IP address refers to the temporary use of a specific IP address during a single interaction or “session” between a client and a server. A session IP may…

A session is a temporary connection between two devices or between a user and a website that lasts for a defined period of activity. When you log in to a…

A shared IP is an IP address that’s used by multiple users, devices, or websites at the same time rather than being assigned to just one. Most shared IP setups…

A static IP address is a fixed IP address that stays the same every time you connect to a network. Unlike a dynamic IP address, which is automatically assigned by…

A subnet is a logical division of an IP network into smaller parts. “Subnet” is short for “subnetwork.” Every IP address has two components: a network ID (which identifies the…

A transit provider is an internet service provider (ISP) that sells access to the global internet by allowing another network’s traffic to pass through its infrastructure. In practice, a transit…

A transparent proxy is a server that intercepts your internet traffic without requiring any configuration on your device and without hiding your IP address. It operates at the network level,…

A VPN (virtual private network) is a service or app that encrypts your internet traffic; it’s a whole system for securing connections. A VPN server is one part of that…

A VPN tunnel is a secure, encrypted connection between your device and a VPN server that protects your data as it travels across the internet. A VPN tunnel does two…

A VPN, or Virtual Private Network, is a technology that creates an encrypted connection between your device and the internet by routing your traffic through a remote VPN server. This…

A whitelist, sometimes called an allowlist, is a security control that defines exactly which IP addresses are permitted to access a network, system, or application, and blocks everything else by…

An ASN lookup is a query that returns information about the organization controlling a specific block of IP addresses. Every network connected to the internet, such as an internet service…

The internet is made up of tens of thousands of separate networks, each operated by one or more different organizations, connected together. An ASN, or Autonomous System Number, is the…

The internet is made up of tens of thousands of separate networks, each independently operated and connected to the others. Each of those networks is called an autonomous system.  Internet…

An edge server is a computer that sits at the outer boundary of a network, positioned geographically close to end users rather than in a centralized data center. Its primary…

An IP address, short for Internet Protocol address, is a unique numerical label assigned to every device that connects to a network. It serves two main purposes: identifying the device…

An IP lease (usually referred to as a DHCP lease) is the way your device “borrows” an IP address on a network for a limited time. When the lease expires,…

An IP lookup is a query that retrieves publicly available information associated with a specific IP address. When you run one, you’re asking a database to return details tied to…

An IP Range is a defined group of consecutive IP addresses treated as a single block. Rather than listing individual addresses one by one, networks use ranges to organize and…

An IP trace is the process of following the path that data takes across a network from one point to another. When you connect to a website or online service,…

An ISP, or Internet Service Provider, is the company that connects you to the internet. Whether you’re browsing at home, streaming on your phone, or working from a coffee shop,…

An open port is a network port that is actively listening for incoming connections. When a port is open, it means a service or application on that device is configured…

Most routing sends data to one specific destination, but anycast routing takes a different approach: the same IP address is assigned to multiple servers in different locations, and traffic is…

In simplest terms, bandwidth is the maximum amount of data that your internet connection can transfer in a specific amount of time. Typically, bandwidth is measured in megabits per second…

Border Gateway Protocol (BGP) is the routing system that keeps the internet running. Think of it like a real-time GPS for your data—every time you load a website, stream a…

Not all internet traffic comes from humans. In fact, a large portion of it comes from bots. “Bot traffic” refers to any of the automated requests made to a website…

As IPv4 addresses became increasingly scarce, ISPs needed a way to serve more customers than they had addresses for. Carrier-grade NAT, sometimes called CGN or CGNAT, is how many of…

“CDN” stands for Content Delivery Network. It is a system of servers distributed across multiple locations around the world. Rather than serving each visitor from a central server, a CDN…

Networks need a way to group IP addresses together, and they do that with CIDR. CIDR stands for Classless Inter-Domain Routing. It’s a method for defining a range of IP…

Connection origin refers to where a network connection starts; a device, system, or endpoint that initiates the connection. Whenever two systems communicate (like your laptop and a website), there are…

DNS propagation is the period of time it takes for a change to a domain’s DNS records to spread across all the DNS servers on the internet. It’s why, after…

DNS, or Domain Name System, is the internet’s system for translating human-readable domain names into the numeric IP addresses that computers use to communicate. When you type a website address…

Dual stack networking is a setup where a network or device runs both IPv4 and IPv6 at the same time. One system can communicate using either protocol, depending on what’s…

Ever tried to watch a video or access a website only to be told the content isn’t available in your region? You’ve encountered geo-blocking in action. Geo-blocking is the practice…

Geolocation is the process of identifying the physical location of an internet-connected device, such as your phone, laptop, tablet, or smart watch, using data signals like GPS, Wi-Fi, cellular networks,…

Hop count is a networking term that tells you how many “steps” (or devices) a piece of data goes through to get from one point to another on a network.…

HTTP, or Hypertext Transfer Protocol, is the foundation of how data is exchanged on the web. When you type a web address into your browser and hit enter, HTTP is…

HTTPS, or Hypertext Transfer Protocol Secure, is the encrypted version of HTTP used to transmit data between a web browser and a server. The “S” stands for secure, and it…

IP allocation is the process of giving out IP addresses to devices, networks, or organizations so they can communicate on a network or the internet. Every device needs a unique…

IP blocking occurs when a website, server, or network refuses to accept traffic from a specific IP address or, in some cases, a range of addresses. It’s a very straightforward…

When data travels across a network, it moves in discrete chunks called packets. Every network has a limit on how large those packets can be, known as the Maximum Transmission…

IP masking is the practice of hiding your real IP address so that websites and online services see a different one instead.  When you connect to the internet normally, your…

Every public IP address is allocated to a specific organization, whether that’s an ISP, a business, a university, or a government agency. IP ownership refers to which organization has been…

IP reputation is a score or classification assigned to an IP address based on its history of online behavior. Security systems use this data to decide whether traffic from a…

IP-based location, also known as IP geolocation, is a way of estimating someone’s physical location based on their IP address. Since every device connected to the internet has an IP…

IPv4 exhaustion is the point at which the internet runs out of new, unused, IPv4 addresses to assign new devices. IPv4 (Internet Protocol version 4) uses a 32-bit address system,…

IPv4, short for Internet Protocol version 4, is the addressing system that has powered the internet since 1983. It’s the format behind every standard IP address you’ve ever seen: four…

The internet runs on addresses. Every device that connects to a network needs a unique IP address to send and receive data. For decades, these addresses followed a format called…

ISP logging is when an internet service provider (ISP) stores records (logs) of your online activity, connections and usage data. What exactly gets logged by your ISP?  Websites (domains) you…

ISP peering is when two internet service providers (ISPs) agree to connect their networks directly and exchange traffic between their customers without paying a third-party transit provider. Instead of sending…

ISP throttling is when an internet service provider intentionally slows a user’s internet connection for certain types of traffic or during specific periods of time. Rather than cutting off access…

When it comes to internet speed, you want to see the lowest latency possible. That’s because latency is a measurement of the amount of time it takes from data to…

When you connect to a website from any device, your IP address is visible to that site, and it can reveal your approximate location. Location spoofing is the practice of…

MTU stands for Maximum Transmission Unit. It’s the largest size a packet can be before it gets sent across a network connection.  MTU is measured in bytes, and every network…

NAT, or Network Address Translation, is a process that allows multiple devices on a local network to share a single public IP address when communicating with the internet. It’s one…

Network congestion happens when a network node or link carries more data traffic than it can efficiently handle, usually leading to reduced quality of service, packet loss, and high latency.…

Network fingerprinting is a technique used to identify a device, system, or user by analyzing how it behaves on a network based on unique characteristics of network traffic such as…

Network reliability refers to how consistently an internet or computer network delivers data without interruption. A reliable network stays up, performs predictably, and recovers quickly when something goes wrong. Several…

Packet loss is what happens when data you send or receive over the internet never makes it to its destination. To understand why that matters, it helps to know how…

Ping is a network utility that tests whether one device can reach another over a network, and measures how long that communication takes. The result is reported in milliseconds and…

Port scanning is the process of probing a device or server to find out which ports are open, closed, or filtered. Since each port corresponds to a specific service or…

Rate limiting is a technique used to control how many requests a user, device, or IP address can make to a server within a set period of time. When that…

Reverse DNS is the process of finding a hostname associated with an IP address. Forward DNS lookup does the opposite: it helps you find an IP address using a hostname.…

You have a router, but do you know what it does? To understand the idea of a router, you have to understand the process of routing.  Every time you load…

Split tunneling is a VPN feature that lets you divide your internet traffic into two separate pathways at the same time. Some traffic routes through the VPN’s encrypted tunnel, while…

When data travels across the internet, it doesn’t move as a continuous stream. Instead, it gets broken into small pieces called “packets.” These packets are sent separately, then reassembled at…

Traceroute (also called tracert on Windows, or tracepath on Linux) is a network diagnostic tool that maps the route your data takes across a TCP/IP network to reach its destination…

Traffic shaping is the practice of managing how data moves through a network by controlling the rate and priority of different types of traffic. Common types of traffic include video,…

When speed matters more than making sure every piece of data arrives, the internet uses UDP. UDP, or User Datagram Protocol, is a way of sending data across a network…

WHOIS is a query-and-response protocol used to look up publicly available registration information about domain names and IP addresses. When you perform a WHOIS lookup, you can retrieve details such…