What Is an IP Address?

What Is an IP Address?

An IP (Internet Protocol) address is a unique numerical label assigned to every device that connects to a computer network using the Internet Protocol. Every time you visit a website, send an email, or stream a video, your device uses its IP address to identify itself and receive data.

IP addresses serve two primary functions: identification (which host or network interface is this?) and location (where is this host in the network topology?). Together, these functions enable the routing of data packets across the global internet.

IPv4 vs IPv6

The internet has two IP address versions in widespread use today:

IPv4 (Internet Protocol Version 4)

IPv4 is the original internet addressing system, using 32-bit numbers written as four decimal octets separated by dots (e.g., 192.168.1.1). This format provides approximately 4.3 billion unique addresses — a number that seemed enormous in 1981 but was largely exhausted by the 2010s due to explosive internet growth.

IPv6 (Internet Protocol Version 6)

IPv6 uses 128-bit addresses written as eight groups of four hexadecimal digits separated by colons (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334). This provides 340 undecillion (3.4 × 10³⁸) addresses — effectively unlimited for any foreseeable future. IPv6 also improves routing efficiency and includes mandatory IPSec security support.

Public vs Private IP Addresses

Public IP Addresses

A public IP address is globally unique and routable on the internet. Your ISP assigns a public IP to your router, and all devices on your network share this single public IP when communicating with external servers. Websites and services see your public IP when you visit them.

Private IP Addresses

Private IP addresses are used within local networks (home routers, office LANs) and are not directly accessible from the internet. RFC 1918 reserves three blocks for private use:

• 10.0.0.0/816.7 million addresses — large enterprise networks
• 172.16.0.0/121 million addresses — medium networks
• 192.168.0.0/1665,536 addresses — home and small office networks

Static vs Dynamic IP Addresses

IP addresses can be static (permanently assigned, never changes) or dynamic (assigned temporarily by DHCP and may change on reconnect or periodically).

How IP Addresses Are Assigned

The global IP address space is managed in a hierarchical system:

1. 1.
   IANA: Internet Assigned Numbers Authority — manages the global IP address pool and allocates large blocks to RIRs.
2. 2.
   Regional Internet Registries (RIRs): ARIN (Americas), RIPE NCC (Europe/Middle East), APNIC (Asia-Pacific), LACNIC (Latin America), AFRINIC (Africa) — allocate blocks to ISPs.
3. 3.
   Internet Service Providers: ISPs receive large IP blocks and allocate smaller ranges to business customers or dynamically assign IPs to residential subscribers via DHCP.
4. 4.
   End Users: Your router receives a public IP from your ISP; your router then assigns private IPs to your local devices via DHCP.

What Your IP Address Actually Reveals

Most people assume their IP address reveals their exact home address. It does not — but what it does reveal is more nuanced than people expect. When we run an IP through our geolocation database, here is what comes back:

Street address, name, phone number — none of these can be determined from an IP address alone. Only your ISP can map your IP to your account, and they only disclose this under a legal court order.

CGNAT — Why Your "Public IP" May Be Shared

Carrier-Grade NAT (CGNAT) is increasingly common, especially on mobile networks and some residential ISPs. With CGNAT, your ISP assigns you a private IP internally and uses a single public IP to represent dozens — sometimes hundreds — of customers simultaneously. From the internet’s perspective, you and your neighbours share one IP address.

This has real-world implications. If one CGNAT customer sends spam or triggers a ban, every customer sharing that IP gets affected. It also makes IP-based geolocation less reliable at the city level, because the public IP is registered under the ISP’s infrastructure address, not the subscriber’s neighbourhood.

Dual-Stack: Having Both IPv4 and IPv6

Modern connections are increasingly dual-stack — meaning your device has both an IPv4 and an IPv6 address simultaneously. When you visit a website, your browser prefers IPv6 if both the site and your ISP support it (via the RFC 6555 "Happy Eyeballs" algorithm). This matters for privacy: if you set up a VPN that only tunnels IPv4 traffic, your IPv6 traffic may bypass the tunnel entirely and reveal your real identity.

You can test your IPv6 connectivity and check whether your connection exposes a dual-stack address using our IPv6 test tool. If you see an IPv6 address there that differs from what your VPN should be showing, your VPN has an IPv6 leak.