IPv4 vs IPv6: Why the Transition Is Taking Decades and IPv4 Still Dominates
IPv4 vs IPv6 is one of the long-running themes in networking: IPv4 is scarce and IPv6 was designed to replace it, yet the transition has taken decades and IPv4 still dominates much of the internet. This post explains why the transition is slow, why IPv4 remains essential, and when you still need to buy or rent IPv4.
What IPv4 and IPv6 Are
IPv4 (Internet Protocol version 4) uses 32-bit addresses—about 4.3 billion possible addresses. It has been the basis of the internet since the 1980s. IPv4 exhaustion—the depletion of free address space at the RIRs—is why we have a secondary market for buying, leasing, and renting IPv4 today.
IPv6 (Internet Protocol version 6) uses 128-bit addresses—effectively unlimited for practical purposes. It was designed to replace IPv4 and solve the address shortage. IPv6 has been standardized and deployed for years, but adoption is incomplete. So IPv4 vs IPv6 is not a simple swap; it’s a long transition in which both coexist.
Why the IPv6 Transition Is Taking Decades
The transition is slow for a few main reasons.
The internet was built on IPv4. Billions of devices, applications, and networks assume IPv4. Upgrading everything takes time, money, and coordination. There is no single “flip the switch” moment.
Partners and customers still use IPv4. Many B2B relationships, hosting providers, and cloud services assume IPv4 or dual-stack. So even if your own network is IPv6-ready, you may still need IPv4 for compatibility.
Dual-stack is the norm. Most large networks run IPv4 and IPv6 side by side. That means IPv4 demand doesn’t go away when IPv6 is added; it stays until IPv6-only or IPv6-dominant becomes realistic end to end.
Inertia and cost. Changing addressing across an organization is costly. Many organizations only add IPv6 where they have to (e.g. mobile carriers, new data centers) and keep IPv4 for the rest.
So IPv4 still dominates in the sense that a large share of traffic and business logic still depends on it. The transition is real but gradual.
Why IPv4 Still Dominates
IPv4 still dominates because:
Traffic share. A large portion of global internet traffic still uses IPv4. IPv6 traffic is growing but has not replaced IPv4 in most regions.
Compatibility. Hosting, cloud, VPN/proxy, and many partners require IPv4 or dual-stack. So organizations that need to reach those partners or use those services need IPv4.
Scarcity and value. IPv4 exhaustion means supply is fixed. That keeps IPv4 valuable and keeps the secondary market (buy, lease, rent) active. IPv6 doesn’t reduce IPv4 value overnight; it reduces it over time as adoption grows.
So when we say IPv4 still dominates, we mean: for many use cases and for the foreseeable future, IPv4 is still required or highly useful. The transition doesn’t change that in the short term.
When You Still Need IPv4
You still need IPv4 when:
Your hosting or cloud requires it. Many providers assume IPv4 or dual-stack. If you’re deploying there, you need IPv4 (buy, lease, or rent) unless the provider is IPv6-only.
Your partners or customers require it. B2B integrations, APIs, and legacy systems often assume IPv4. Compatibility drives IPv4 demand.
You’re building VPN/proxy or similar services. Clean IPv4 blocks are often needed for reputation and scale. See how to rent IPv4 or how to buy IPv4 for options.
You need BYOIP or dedicated space. Bringing your own IP to a cloud provider (BYOIP) typically means IPv4 (or dual-stack). Buying or leasing IPv4 gives you dedicated space for that.
So IPv4 vs IPv6 is not either/or for most organizations—it’s both. You may invest in IPv6 for new capacity and still buy IPv4 or rent IPv4 for compatibility and partners.
What You Should Do
If you’re planning capacity or compatibility:
- Assume dual-stack for the foreseeable future. IPv4 and IPv6 will coexist. Plan for both where it matters.
- Get IPv4 where you need it. If your stack or partners require IPv4, use the secondary market—buy IPv4 for long-term control or rent IPv4 for short-term or flexible use.
- Invest in IPv6 where it pays off. New services, new data centers, and mobile networks often benefit from IPv6. That doesn’t eliminate IPv4 need elsewhere.
IPv4 vs IPv6 is a long game. The transition is real, but IPv4 still dominates for many use cases. Understanding that helps you choose when to buy or rent IPv4 and when to push IPv6—and often, you’ll do both.