IPv4 vs. IPv6: What You Need to Know

We ran out of Internet addresses in 2011. The Internet didn't stop working. How?

The Mathematics of Scarcity

IPv4 uses 32 bits for addresses: 2³² = 4.3 billion possibilities. In the early 1980s, when most of humanity had never touched a computer, this felt infinite.

It wasn't.

By 2011, we'd assigned the last block¹. Every IPv4 address that would ever exist already existed. Yet here you are, reading this. Your phone has an address. Your laptop has an address. Your smart fridge, inexplicably, has an address.

The answer is Network Address Translation—a hack where dozens of devices share one public address by hiding behind a router that rewrites packets on the fly. It works. It's clever. It's also like solving a housing crisis by making everyone sleep in shifts. Nobody would design it this way on purpose.

IPv6 is the actual solution: 128-bit addresses. You could assign a trillion addresses to every atom in your body and barely make a dent. We're not running out.

What Changed Besides the Number

IPv6 isn't just "more addresses." The protocol was rebuilt from scratch with decades of hindsight about what the Internet actually needed.

Simpler routing. IPv4 headers grew organically, accumulating fields as needs arose. IPv6 has a fixed 40-byte header. Routers process it faster because there's less to parse.

No fragmentation in the network. IPv4 routers can split oversized packets into smaller pieces. Sounds helpful—it's actually expensive and error-prone. IPv6 pushes fragmentation to the endpoints. The network just moves packets.

Auto-configuration. Plug a device into an IPv6 network and it generates its own valid address without asking anyone. No DHCP server required. It just works.

Multicast replaces broadcast. IPv4 broadcast wakes up every device on the network, even if only one cares. IPv6 multicast lets devices opt into groups. Traffic goes where it's wanted.

End-to-end connectivity restored. NAT breaks the Internet's original design—any device talking directly to any other device. IPv6 restores it. Every device gets a real, routable address. No translation layers. No port forwarding gymnastics. Video calls and peer-to-peer applications work the way they were supposed to.

The Notation Problem

IPv4 addresses look like this: 192.168.1.1

Four numbers, each 0-255. Human-readable. Memorable.

IPv6 addresses look like this: 2002:0de6:0001:0042:0100:8c2e:0370:7234

Eight groups of hexadecimal digits. Not human-readable. Not memorable.

You can abbreviate them—drop leading zeros, replace consecutive zero groups with ::. But nobody is going to remember their IPv6 address the way they remember 192.168.1.1.

DNS exists so you don't have to remember addresses. IPv6 optimizes for machines, not humans. That's a reasonable trade.

The Adoption Paradox

Global IPv6 adoption sits around 45-50%². Some countries exceed 70%. T-Mobile USA runs over 90% IPv6. The technology works. The benefits are real.

So why isn't it everywhere?

Because nothing forces it. IPv4 still works. NAT still works. For most users, there's no visible difference. The pain of address exhaustion falls on network operators and cloud providers, not end users. And those operators already deployed NAT to cope.

Meanwhile, upgrading to IPv6 means touching everything: routers, firewalls, applications, monitoring tools, security policies. It's not technically hard—it's logistically hard. Every ISP, every enterprise, every home router manufacturer has to move.

The result: a slow, decade-spanning transition where both protocols run in parallel. Dual stack. Tunneling. Translation gateways. All the machinery to let the old Internet and the new Internet coexist.

We standardized IPv6 in 1998³. It's objectively better. We're still only halfway there. "Good enough" is the enemy of "actually good."

Why This Matters

IPv6 isn't a version bump. It's a different philosophy.

IPv4 was designed for a small, trusted network of research institutions. It grew into the global Internet through clever workarounds—NAT, private address spaces, CIDR, increasingly baroque routing.

IPv6 was designed for the Internet we actually have: billions of devices, untrusted networks, global scale from day one. It assumes hostile traffic. It assumes mobile devices changing networks constantly. It assumes you want video calls and real-time gaming to actually work without NAT traversal hacks.

The transition is invisible to most people because engineers work hard to make it so. But underneath, the Internet's addressing foundation is being rebuilt—highway replaced while traffic keeps moving.

When you notice IPv6 addresses in your network logs, or your ISP mentions "improved connectivity," you're watching one of the largest infrastructure migrations in history. Slow. Quiet. Still happening.

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