# IPv4 vs IPv6
Confidence: high
Last verified: 2026-05-22
Generation: human_only


## TL;DR

IPv4 (1981) uses 32-bit addresses (~4.3 billion). IPv6 (1998) uses 128-bit addresses (340 undecillion). IPv4 exhausted in 2019 (last /8 allocated). IPv6 adoption: ~45% globally (2025). IPv6 eliminates NAT (every device gets public IP) and simplifies header format.

## Core Explanation

IPv4: `192.168.1.1`, NAT needed due to address shortage. IPv6: `2001:db8::1`, no broadcast (uses multicast), built-in IPsec, autoconfiguration (SLAAC), larger payload. Key challenges: dual-stack transition, legacy application compatibility. Most cloud providers and CDNs (Cloudflare, AWS) support IPv6.

## Further Reading

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