How to Buy Global IPv4: A Beginner's Guide

IPv4 addresses are numeric labels that help devices communicate online. 

With most freely available registry pools exhausted, buyers often turn to the secondary market. 

Buying IPv4 generally means receiving the registered right to use an address block under a Regional Internet Registry's (RIR's) policies, rather than purchasing ordinary property.

A quick glossary

• Block: a range of addresses written in CIDR notation. A /24 contains 256 addresses.
• RIR: one of five regional registries (ARIN, RIPE NCC, APNIC, LACNIC and AFRINIC) that record who holds internet number resources.
• ROA: a digitally signed record in the Resource Public Key Infrastructure (RPKI) system. It identifies which network, using its autonomous system number (ASN), may announce your block.
• IRR: Internet Routing Registry databases. Many networks use their records to decide which routes to accept.
• Reverse DNS (rDNS): maps an IP address back to a hostname. Mail systems often check it.
• Reputation: a block's history of spam or other abuse, including whether its addresses appear on blocklists.

Step 1: Waitlist, buy or lease

Waitlist. Some registries, including ARIN, operate waiting lists for returned space. Supply is limited and unpredictable, and addresses received this way may carry restrictions on later transfers. 

Check current availability and conditions before relying on this route.

Buy. A transfer through a broker or marketplace makes you the registered holder of an existing block, subject to registry approval. 

This gives you more control over sourcing than a waitlist, though completion dates aren't guaranteed.

Lease. Platforms such as IPXO let you rent addresses for a period. Leasing doesn't change the registered holder and can suit short-term or uncertain needs. 

Check renewal terms and what happens when the lease ends.

Step 2: Choose a region and check eligibility

Each block is registered with a specific RIR. Transfers between regions are possible only where both registries' policies permit them. 

Confirm that the proposed transfer route is allowed before paying a deposit. Requirements differ by registry:

• ARIN: the minimum transfer size is a /24, and recipients generally need to document their address needs.
• RIPE NCC: IPv4 transfers are subject to holding-period rules, so the block's allocation and transfer history matters.
• APNIC: check recipient eligibility, applicable transfer fees and whether pre-approval is available for your transaction.

A block's registration region doesn't guarantee that every hosting provider will accept it. 

Confirm that your provider supports customer-owned IPv4 addresses, the block size you're buying and your planned routing arrangement.

Step 3: Where to shop

Auction marketplaces let buyers bid on listed blocks. Fixed-price listings show an asking price without a bidding process. Full-service brokers can handle sourcing and coordinate registry requests for a fee.

Use escrow with clear release conditions: a neutral party holds the money until the agreed transfer requirements are met. 

Confirm who holds the funds, what triggers release and what happens if the registry rejects the transfer.

IPv4 Connectoffers fixed-price listings, a blacklist report per subnet and transfer assistance across ARIN, RIPE NCC and APNIC.

Step 4: Run due diligence before you commit

• Reputation. Check addresses across the block using tools such as the Spamhaus IP and Domain Reputation Checker. Review any listings and their causes. A few clean sample addresses don't establish the reputation of the entire block.
• Registrant. Look up the block in the relevant RIR's registration records. Confirm both the listed holder and the seller's authority to approve the transfer.
• Routing records. Identify IRR records and ROAs that still point to the seller's network. Agree who will update or remove them during handover.
• Reverse DNS. Agree who will control rDNS and when, especially if you plan to send email.
• Special-purpose space. Confirm the block is eligible for ordinary public internet use, not private or reserved space.

Step 5: Complete the transfer correctly

Seek recipient pre-approval where available. 

The seller and buyer typically submit coordinated requests, and the registry checks both parties before updating its records. 

Follow the registry's required sequence and your escrow agreement rather than assuming every transfer follows the same workflow.

1. Confirm eligibility and submit the required recipient documents.
2. Fund escrow under the agreed payment and release terms.
3. Obtain registry approval and confirm that the registration record has changed.
4. Coordinate routing with your provider. Create ROAs for the ASN that will announce the block and add or update IRR route records.
5. Set reverse DNS records and test reachability.
6. If you'll send legitimate email, increase volume gradually while monitoring delivery results.

Step 6: Budgeting

Get current quotes for comparable blocks rather than relying on a market-wide average. Size, region, reputation and availability can all affect the price per address. Ask whether the quoted price includes broker and transfer fees.

Compare the full cost of buying with leasing or using provider-assigned addresses. 

Include registry membership or recurring fees, hosting and routing charges, and engineering time for DNS, routing and monitoring.

Common mistakes to avoid 

• Buying without checking the reputation of the actual block.
• Skipping ROA and IRR updates, which can cause other networks to reject your routes.
• Relying on seller assurances without checking registry records and signing authority.
• Assuming your hosting provider will accept any purchased block.
• Expecting geolocation databases to update immediately after the transfer.

After the transfer

Geolocation providers maintain their own databases. 

Check where your addresses appear to be located and submit corrections where needed; MaxMind, for example, has a public correction process. 

Updates follow each provider's schedule, not the registry's.

Continue monitoring reputation, routing and reverse DNS after handover. Real-time monitoring of network traffic can also surface unusual activity on newly announced addresses early.

Keep the transfer records and seller contact details available in case an inherited abuse listing or outdated record needs resolving.

Wrapping up

Buying IPv4 requires both a registry transfer and a technical handover. 

Confirm eligibility, verify the block independently, agree on escrow conditions and coordinate routing before putting the addresses into service. 

Use your registry's current policies as the final reference for requirements and restrictions.