The IPv4 Transfer Market Explained
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The IPv4 transfer market exists because the free pools of IPv4 addresses are exhausted: organizations that need more addresses now obtain them from organizations that no longer use them. The address space changes hands under a commercial agreement, and the Regional Internet Registry responsible for it records the new holder and publishes the transfer in its transfer log. Those logs are public, which makes it possible to measure the market - how many addresses move each month, between which regions and in which block sizes.
Why there is an IPv4 market
IPv4 has about 4.3 billion addresses, of which a significant share (multicast and the former class E range alone account for about one in eight) is reserved for special purposes. For decades the registries handed out addresses from free pools on the basis of documented need. IANA allocated its last free blocks to the five Regional Internet Registries in 2011, and between 2011 and 2015 APNIC, RIPE NCC, LACNIC and ARIN reached the end of their regular free pools; AFRINIC entered its own exhaustion phases later.
Demand did not stop. IPv6 adoption has grown, but most services still need IPv4 connectivity, and every new hosting platform, ISP or cloud region needs public IPv4 addresses for at least part of its customers. The registries therefore introduced transfer policies that let holders pass unused space to others. The result is a market: prices are set privately between buyer and seller (often with a broker), while the registries record who holds what.
How a registry transfer works
The details differ by registry, but a transfer typically follows these steps:
- Buyer and seller agree on a block and a price. Brokers often match the parties and handle escrow, but they are not required.
- Both parties confirm their eligibility with the registry. Depending on the RIR, the recipient may have to justify its need for the addresses, and both must hold the right membership or service agreement.
- The registry checks that the seller is the legitimate holder, approves the transfer and updates its database: the block's registration now points to the new holder.
- The transfer appears in the registry's public transfer log, with the date it was processed, the block and, depending on the registry, the organizations and countries involved.
- The new holder takes over operations: RPKI ROAs, IRR route objects, reverse DNS delegation, abuse contacts and geolocation data all have to be updated before the block is announced from the new network.
Registry policies also set limits that shape the market, such as minimum transfer sizes and holding periods during which recently received space cannot be transferred again. The smallest block that is widely accepted in the global routing table is a /24 (256 addresses), so that is the practical minimum for space meant to be routed independently.
Types of transfers
| Type | What it is | In the logs |
|---|---|---|
| Market transfer (intra-RIR) | A sale between two organizations in the same registry's region. | Listed by that registry. |
| Inter-RIR transfer | Address space moves from one registry's region to another, for example from ARIN to APNIC. Requires compatible transfer policies in both registries; ARIN, APNIC, LACNIC and RIPE NCC have them, while AFRINIC does not take part in inter-RIR transfers at the time of writing. | Listed by both registries. See inter-RIR transfers. |
| Merger or acquisition | The holder changes because one company bought or merged with another; no separate sale of addresses. | Usually listed in the same logs; several registries mark them with a separate merger/acquisition type. |
| ASN and IPv6 transfers | AS numbers and IPv6 blocks can be transferred too, depending on the registry policy either as market transfers or only as part of M&A. | Listed alongside IPv4 transfers. |
Leasing is not a transfer. A lessee uses addresses while the registration stays with the lessor, so leases do not appear in any transfer log. The logs therefore measure changes of holder, not who actually announces a block in BGP.
Reading the transfer logs and statistics
Each RIR publishes its transfers in its own format. ipctl.io imports the logs of all five registries daily, normalizes them (dates, resources, organizations, countries), removes the duplicate entry that both registries publish for an inter-RIR transfer, and counts IPv4 volume as the number of addresses in each transferred block. On that basis you can:
- See the current market: IPv4 transfer statistics with monthly volume, inter-RIR flows, top countries and the latest transfers, and the same view per registry.
- Look back in time: the archive by year and month has a page for every month with volume per RIR, block sizes and the largest transfers.
- Follow address space between regions: the inter-RIR page shows all-time and recent flows and the net balance per registry.
- Check one block or network: prefix and ASN pages include their transfer history, and the transfer search finds transfers by prefix, IP, ASN, organization or country.
Keep three caveats in mind. Transfer dates are the dates the registry processed the transfer, not the date of the sale. Not every registry publishes organization names and countries for every transfer, and some only started recently, so country rankings for older years undercount some regions. And because prices are private, the logs say nothing about what addresses cost.
Due diligence before buying or leasing a block
A block's history travels with it. Before taking over address space, check:
- Registration and transfer history: who held the block before, and how often it changed hands. The prefix page shows its registry data and transfers.
- Routing history: whether the block is currently announced, by which origin AS, and whether existing ROAs would make your announcement RPKI-invalid until they are replaced.
- Reputation: whether addresses in the block are listed for spam, scanning or other abuse. Run a few addresses through the IP reputation check; listings can take time to clear after the holder changes.
- Geolocation: databases may still place the block in the previous holder's country. Publish a geofeed and plan time for the change to propagate.
Frequently Asked Questions
Can IPv4 addresses be bought and sold?
Yes. All five Regional Internet Registries allow holders to transfer IPv4 space to other organizations under their transfer policies. The sale is a private agreement; the registry records the new holder and publishes the transfer.
What is an inter-RIR transfer?
A transfer in which address space moves from one registry's region to another's, for example from ARIN to RIPE NCC. Both registries need compatible policies and both list the transfer. See the inter-RIR statistics.
How many IPv4 addresses are transferred each year?
It varies by year and registry. The archive shows the number of transfers and the IPv4 addresses moved for every year and month since the logs began, computed from the five RIR transfer logs.
Do the transfer logs show prices?
No. Registries record who holds the addresses, not what was paid. Where price information exists, it comes from brokers and marketplaces.
Is leasing IP addresses the same as a transfer?
No. In a lease the registration stays with the original holder, so nothing appears in the transfer logs. Only a change of holder is a transfer.
Where can I download the RIR transfer data?
Each registry publishes its own transfer log on its website. ipctl.io combines all five, normalizes them and makes them browsable on the transfer pages and searchable with the transfer search, updated daily.