IPv4 vs IPv6
IPv4 uses 32-bit addresses (4.3 billion total) written as dotted decimals like 203.0.113.42. The pool is exhausted, which is why ISPs increasingly share addresses via CGNAT. IPv6 uses 128-bit addresses (3.4 × 10³⁸ total) written in hexadecimal like 2001:db8::1. Both can coexist, and most modern devices use both simultaneously (dual-stack).
Public vs private addresses
Three IPv4 ranges are reserved for private networks: 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. Your router uses one of these internally and translates (NAT) outbound traffic to your single public IP. IPv6 has a similar concept (unique local addresses) but the abundance of public addresses means most IPv6 hosts get a globally routable address directly.
Static vs dynamic
Dynamic IPs are assigned by your ISP from a pool and can change. Static IPs are permanently assigned to you. Static is required for: running publicly accessible servers, certain site-to-site VPNs, and some specialized firewall rules. For everything else, dynamic is fine — and using a dynamic DNS service can bridge the gap.
How geolocation works
IP geolocation databases map address ranges to approximate locations based on registration records and observed behavior. Accuracy is good at the country level (~95%+) and OK at the city level. It cannot determine a street address or identify an individual user without additional information.
Security considerations
- Your public IP is visible to every server you connect to — that's how the internet works, not a leak.
- A VPN replaces your visible IP with the VPN provider's, useful for privacy and bypassing geo-restrictions.
- Open ports on your public IP are scanned constantly. Never expose services without authentication, even on a "random" port.
- For business networks, use firewall rules and a reverse proxy rather than exposing internal services directly.