IPv4 vs IPv6
The two versions of the Internet Protocol and why IPv6 is the long-term answer.
8 min readTechnical guideUpdated 2026
The big picture
IPv4 has been the standard since the 1980s, but the address pool is exhausted. IPv6 expands the address space dramatically and simplifies routing for modern internet scale.
Snapshot
IPv4
- 32-bit addresses
- Format: 192.168.1.1
- About 4.3 billion addresses
- NAT required at scale
IPv6
- 128-bit addresses
- Format: 2001:db8::1
- 340 undecillion addresses
- No NAT required
Detailed comparison
| Feature | IPv4 | IPv6 |
|---|---|---|
| Address length | 32 bits | 128 bits |
| Address format | Decimal | Hexadecimal |
| Security | Optional IPsec | Built-in IPsec support |
| Auto configuration | DHCP/manual | SLAAC + DHCPv6 |
| Header size | Variable | Fixed 40 bytes |
| QoS support | Limited | Native traffic classes |
| Multicast | Limited | Enhanced |
Advantages
IPv4 strengths
- Universal support across legacy systems
- Simple addressing format
- Mature tooling and documentation
IPv6 strengths
- Massive address space
- Better routing efficiency
- Improved auto-configuration
- Reduced reliance on NAT
Why IPv4 is running out
Address exhaustion
IPv4 offers about 4.3 billion addresses. With global growth, the free pool has been exhausted, forcing workarounds like NAT.
IoT growth
Billions of connected devices require unique addresses. IPv6 scales without complex translations.
Adoption snapshot
25%
Google users on IPv6
40%
Major websites with IPv6
35%
Mobile networks with IPv6
Adoption continues to climb as providers modernize infrastructure.