Glossary of IP and Networking Terms

Short definitions of the terms used across FindMyIPLocation. Follow the links for full guides.

A–C

ASN (Autonomous System Number)

A number that identifies a network that routes its own traffic on the internet, such as an internet provider or a cloud company. Example: AS15169 is Google. Learn more.

CAA record

A DNS record that says which certificate authorities may issue SSL/TLS certificates for a domain.

CGNAT (Carrier-grade NAT)

A technique providers use to share one public IPv4 address between many customers. Learn more.

CIDR

A short way to write an IP address range: an address plus the number of fixed bits, such as 192.168.1.0/24 for 256 addresses. Learn more.

CNAME record

A DNS record that makes one domain name an alias of another.

D–H

DHCP

The protocol your router uses to hand out local IP addresses to devices automatically. Learn more.

Default gateway

The router your device sends all internet traffic to, usually at an address like 192.168.1.1. Learn more.

DDoS

An attack that floods a server or connection with traffic from many sources. Learn more.

DKIM

An email signature that proves a message was sent by the domain it claims and was not changed on the way. Learn more.

DMARC

An email policy that tells receivers what to do when SPF and DKIM checks fail, and where to send reports.

DNS (Domain Name System)

The internet's address book: it translates names like example.com into IP addresses. Learn more.

DNS over HTTPS (DoH)

Encrypted DNS lookups sent over HTTPS, so your network cannot read them. Learn more.

DNS leak

When your device sends DNS queries outside your VPN tunnel, revealing the sites you visit to your provider. Learn more.

DNSBL

A DNS-based blacklist of IP addresses known for sending spam. Learn more.

Dedicated IP

An IP address used only by you, for hosting, email or a VPN. Learn more.

Dynamic IP

An IP address that can change over time. Most home connections have one. Learn more.

Geolocation

Estimating the physical location of an IP address. Learn more.

I–N

IP address

The number that identifies a device or connection on a network. Learn more.

IP allowlisting

Allowing only approved IP addresses to reach a service. Learn more.

IPv4

The original IP version, with addresses like 203.0.113.42. About 4.3 billion addresses exist.

IPv6

The newer IP version, with addresses like 2001:db8::1. It has an almost unlimited number of addresses. Learn more.

ISP (Internet Service Provider)

The company that connects you to the internet and assigns your public IP address. Find yours.

HTTPS

The encrypted version of HTTP that protects the connection between your browser and a website. Learn more.

Localhost

The name for your own computer, at address 127.0.0.1 (IPv4) or ::1 (IPv6). Learn more.

MAC address

A hardware identifier for a network interface, used only inside your local network. Learn more.

MX record

A DNS record that names the mail servers that receive email for a domain.

NAT (Network Address Translation)

The method your router uses to let many devices share one public IP address. Learn more.

P–S

Ping

A command that tests whether a host is reachable and measures the round-trip time. Learn more.

Port

A number from 0 to 65535 that identifies a service on a device, such as 443 for HTTPS. Common ports.

Port forwarding

A router rule that sends incoming traffic on a port to a device on your network. Learn more.

Private IP address

An address reserved for local networks, such as 192.168.1.20. It never appears on the public internet. Learn more.

Proxy server

A server that forwards your requests, so websites see its IP instead of yours. Learn more.

PTR record

The DNS record used for reverse DNS: it maps an IP address to a hostname. Learn more.

Public IP address

The address the internet sees for your connection. The home page shows yours.

RDAP

The modern, structured replacement for WHOIS. Learn more.

Reverse proxy

A server in front of websites that receives visitors' requests, used by CDNs and DDoS protection.

Router

The device that connects your home network to the internet. It usually has a local address like 192.168.1.1. Learn more.

SPF

A DNS record that lists which servers may send email for a domain.

Spoofing

Faking the sender of a packet or email. See IP spoofing and email spoofing.

Static IP

An IP address that does not change. Servers and many businesses use one.

Subnet mask

A number such as 255.255.255.0 that marks which part of an IP address is the network and which part is the device.

T–Z

Traceroute

A command that lists every router between you and a destination. Learn more.

Tor

A free network that hides your IP by routing traffic through three volunteer servers. Learn more.

TTL (Time to live)

For DNS, how many seconds a record may be cached before it is looked up again.

VPN (Virtual Private Network)

A service that encrypts your traffic and routes it through its server, hiding your IP from websites. Learn more.

WebRTC

A browser technology for real-time audio and video that can reveal your IP address. Learn more.

WHOIS

A lookup service for the owner and registration details of domains and IP ranges. Try our WHOIS lookup.