IPv4 vs IPv6: Why We Ran Out of Addresses

IPv4 uses 32-bit addresses, creating approximately 4.3 billion unique addresses. This seemed infinite in 1981 but proved insufficient as smartphones, IoT devices, and cloud computing proliferated. IANA exhausted its IPv4 pool in January 2011. ARIN ran out in September 2015. IPv6 uses 128-bit addresses, providing 340 undecillion addresses, enough for every atom on Earth to have its own address. Adoption has been slow: as of 2025, only about 40 percent of Google traffic comes over IPv6. The transition requires operating systems, routers, ISPs, and websites to all support the new protocol. Network Address Translation extended IPv4 lifespan but introduced complexity.