Glossary · Protocols
IPv4: definition, explanation, and why it matters
Internet Protocol version 4 — the original 32-bit addressing scheme used to identify devices on the internet, written as four decimal numbers like 192.168.1.1.
Definition
Internet Protocol version 4 — the original 32-bit addressing scheme used to identify devices on the internet, written as four decimal numbers like 192.168.1.1.
Plain-English explanation
IPv4 provides about 4.3 billion unique addresses. The internet exhausted the global free pool of these in the 2010s, which is why ISPs increasingly use NAT, CGNAT, and IPv6 to keep growing.
An IPv4 address consists of four octets (0–255) separated by dots. Some ranges are reserved for private networks (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) and never route on the public internet.
Real-world examples
- 8.8.8.8 (Google DNS), 1.1.1.1 (Cloudflare DNS), 192.168.1.1 (a common home router LAN address).
Why it matters
Despite IPv6's growth, IPv4 still carries the majority of public internet traffic. Understanding its limits is essential to understanding NAT, port forwarding, and why some peer-to-peer applications struggle.
Common misconceptions
- Myth: Every device gets a public IPv4 address.
Reality: Most home devices share one public IPv4 via NAT. Increasingly, even the home router shares an IPv4 with neighbors via carrier-grade NAT.
Frequently asked questions
- What does '192.168.x.x' mean?
- It's a private IP range used inside home and office networks. These addresses never appear on the public internet.