What Is My IP – Free Online IP Checker

What Is a Public IP Address?

Your public IP address is the identifier your router or firewall presents to the rest of the internet. Every device behind it — laptops, phones, servers — usually shares this one address through NAT (Network Address Translation), the same way an office building shares a single street address even though every desk inside has its own extension.

When you whitelist an address in a firewall rule, set up port forwarding, or configure a remote-access VPN, this is the address the other side needs to know about — not the private 192.168.x.x or 10.x.x.x address your device shows locally.

Why Checking Your Public IP Matters

• Firewall whitelisting. Vendors, VPN gateways, and cloud services often restrict access by source IP — you need the exact public address to add to their allow list.
• Port forwarding and remote access. Connecting to a home lab, NVR, or self-hosted service from outside your network means dialing this address, not a private one.
• Confirming VPN or proxy status. If your IP doesn't change after connecting to a VPN, traffic isn't routing the way you expect.
• Dynamic DNS troubleshooting. If a DDNS hostname isn't resolving correctly, comparing it against your current public IP is the fastest way to spot a stale record.
• Geolocation and CDN behavior. Your public IP is what services use to guess your region — useful for explaining unexpected content restrictions or routing.

Key Terms to Know

• Public IP — the address visible to the internet, assigned by your ISP.
• Private IP — the internal address a device uses on its own LAN; never routable on the public internet.
• NAT — Network Address Translation, the process your router uses to map many private addresses to one public one.
• Hostname — the reverse-DNS name associated with an IP, often revealing the ISP or hosting provider.
• Dynamic vs. static IP — most home connections get a dynamic (changing) public IP, while businesses often pay for a static one.
• IPv4 vs. IPv6 — IPv4 addresses look like 203.0.113.10; IPv6 addresses are longer and hex-based, like 2001:db8::1.

Quick Reference: Private & Reserved Ranges