IPv4 vs IPv6 — What's the Difference?
IPv4 uses 32-bit addresses (like 192.168.1.1), providing about 4.3 billion unique addresses; IPv6 uses 128-bit addresses (like 2001:0db8::1), providing a vastly larger address space designed to outlast IPv4's exhaustion.
Published October 4, 2026
IPv4 uses 32-bit addresses (about 4.3 billion, written like 192.168.1.1) and has run out; IPv6 uses 128-bit addresses (written in hex like 2001:db8::1) giving a practically unlimited supply.
The concept
IPv4 relies on NAT to let many devices share one public address. IPv6 gives every device a globally routable address, removing the need for NAT.
IPv6 also simplifies headers and builds in autoconfiguration. Most networks run both (dual stack).
Address formats
Practical examples
Test both
ping -4 example.com
ping -6 example.comDNS records
A example.com → 203.0.113.42
AAAA example.com → 2001:db8::1Bind a server to IPv6
server.listen(3000, '::') // dual-stack on most systemsIPv6 in URLs
http://[2001:db8::1]:8080/Common mistakes
- Storing IPs in a VARCHAR(15) column (IPv6 needs up to 45).
- Forgetting square brackets around IPv6 in URLs.
- Skipping the AAAA record.
Key takeaways
- 32-bit vs 128-bit.
- A vs AAAA records.
- Support both.
FAQ
Is IPv6 faster?
Not inherently, though removing NAT can simplify paths.
Will IPv4 disappear?
Not soon; both will coexist for years.