Why IPv4 still costs money in the IPv6 era
The successor protocol has been finished for a quarter of a century, every modern device speaks it, and its address space is so large that exhaustion is a joke rather than a risk. And yet a /24 of the old protocol still costs thousands of dollars, an entire industry brokers, leases and securitises it, and this site exists largely to check its history. The paradox has a mechanical explanation, and if you hold or need address space, the mechanics are worth understanding.
The paradox, stated plainly
IPv4 has about 4.3 billion addresses and the registries handed out the last free ones in the 2010s. IPv6 has more addresses than there are grains of sand, is issued generously for the cost of paperwork, and has been production-ready for decades. If addresses were the product, the old ones would be worthless. They are not worthless, because addresses were never the product. Reachability is.
Reachability is the product
A server exists to be reached by clients, and a meaningful share of the world's clients still sit on networks that reach only IPv4, or reach IPv6 poorly. A service that wants every customer must therefore be reachable over IPv4, whatever else it also speaks. That single fact props up the entire market: v6 adoption has climbed for years, roughly half of traffic to major platforms arrives over it, and the remaining half is made of exactly the customers no business will volunteer to lose. Dual-stack, running both protocols, is the standard answer, and dual-stack means every serious deployment still needs IPv4, which means demand persists against a fixed supply. Price follows.
The machinery that stretches IPv4
Scarcity bred machinery for using fewer real addresses, and the machinery itself explains several things this blog covers. Carriers put thousands of subscribers behind single public addresses with carrier-grade NAT, which conserves space at the cost of making an address mean a crowd. Hosts multiplex many websites behind one address. Translation gateways let v6-only networks reach the v4 internet through shared pools. Every one of these substitutes capital equipment and complexity for addresses, and their operating cost is effectively the ceiling on what an address can be worth: an operator pays for IPv4 only while it is cheaper than the machinery that avoids it.
What the market has actually done
Priced like the strategic asset it accidentally became, and not in a straight line. The market's founding transaction was Microsoft buying Nortel's addresses at $11.25 apiece in 2011; prices peaked around $60 per address in 2021, then corrected hard, with ordinary blocks settling to roughly half the peak by 2024 and large blocks falling to ten-year lows through 2025 before the market turned upward again in mid-2026. Alongside the sale market, a leasing market matured at rates around half a dollar per address per month, letting holders earn on space instead of selling it. The honest reading of that history is that nobody, including the people quoting prices, has reliably predicted this market, and this post will not try. What has stayed true through every swing: clean, well-documented space commands the premium, and history is what clean means.
What it means for buyers and holders
- If you need addresses, the choice is buy, lease, or engineer around with the machinery above, and the right answer follows your time horizon. Whichever you choose, the block's history moves its real value more than the market's direction does.
- If you hold addresses, idle space is a yielding asset now: leasing exists precisely because demand outlives the free pool. The reputation of your space is the asset's condition, and a careless lessee can spend it.
- For both, deploy IPv6 alongside rather than instead. Dual-stack is cheap, future-proofs the deployment, and quietly reduces how much IPv4 you must pay for, which is the only guaranteed way to win against a price you cannot predict.
The IPv6 part of your report
None of this makes IPv6 space uninteresting, only differently interesting. A v6 block is too cheap to be scarce, so its value is entirely in what it has done: the network announcing it, the reputation its addresses have earned, and how long it has been where it is. The questions are the same ones this site answers for IPv4, which is why lookups here handle both families everywhere, addresses, prefixes and the networks behind them. Scarcity made IPv4 history valuable enough to build a site around; behaviour makes IPv6 history worth reading too, and the habit of checking before trusting transfers between protocols unchanged.
Look up any IPv4 or IPv6 address, prefix or AS number on the front page. The report shows the history that decides what space is really worth, names the source and date behind each fact, and says plainly when nobody has checked something.