Buying and selling IPv4 addresses on the secondary market is now the primary way organizations acquire or monetize routable public IPv4 space. With no free pools available from any Regional Internet Registry (RIR), transactions involve careful due diligence, policy compliance, secure processes, and strategic timing to maximize value and minimize risks.

This category offers step-by-step, practical guides for both buyers and sellers—covering everything from initial valuation and sourcing to final transfer completion—so ISPs, enterprises, cloud providers, hosting companies, data centers, and individual legacy holders can execute transactions confidently and efficiently.

Why Buying & Selling Guides Are Essential
IPv4 remains a valuable, finite asset critical for network expansion, email deliverability, outbound connectivity, dual-stack compatibility, and legacy system support. Successful transactions depend on:

Understanding current market dynamics and regional variations
Complying with RIR policies (justified need, transfer rules, lock periods)
Protecting against fraud, dirty blocks, routing issues, or failed transfers
Optimizing price through proper preparation and negotiation

Key Topics Covered

Buyer guides: How to find reputable sellers/brokers, evaluate block quality (cleanliness, routing history, provenance), perform due diligence (blacklist checks, IRR/RPKI verification, WHOIS history), prepare justified need documentation, and complete secure transfers
Seller guides: Maximizing value (timing sales, block sizing strategy, clean-up before listing), preparing documentation (utilization proof, org details), choosing listing methods (broker, marketplace, direct), and handling post-sale routing/return obligations
Valuation basics: Factors influencing price (block size, region, cleanliness, legacy status, routing readiness), common pricing models, and how to benchmark offers
Transaction process: Step-by-step walkthroughs for intra-RIR and inter-RIR transfers, required forms, timelines, fees, and common rejection reasons (insufficient need, policy violations)
Escrow & security best practices: Using trusted escrow services, verifying counterparty identity, securing LOAs (Letter of Authorization) for routing, and protecting against hijacks or disputes
Broker vs direct deals: Pros/cons of working with brokers (expertise, clean inventory, faster execution) vs direct peer-to-peer (potentially lower fees, but higher risk and effort)
Risk mitigation: Avoiding scams, dirty or contested blocks, legacy pitfalls, anti-flip restrictions, and post-transfer issues (BGP announcement failures, reverse DNS setup)
Legacy & special cases: Handling pre-RIR legacy blocks, M&A transfers (8.2-style), and compliance with regional nuances (ARIN needs-based vs RIPE permissive)

Whether you’re acquiring IPv4 to scale your network, bypass waitlists, or monetize unused holdings, these articles provide checklists, real-world examples, and best practices drawn from RIR policies, operator experiences, and secondary market norms. Bookmark for reference—successful IPv4 transactions hinge on preparation, compliance, and trusted processes.

12