How to Read an IPv4 Availability Map
All ~4.3 billion IPv4 addresses are allocated, so availability no longer means free space — it means space that is registered but silent. Here is how a three-layer map finds it.
Availability used to mean free space — now it means silence
The free pools are gone. Between 2011 and 2020, the regional registries handed out the last of the unallocated space, and all ~4.3 billion IPv4 addresses are now allocated to somebody. That quietly changes what an "availability map" can show: there is no unassigned greenfield left to plot. What still exists in quantity is space that is allocated, paid for and idle — registered to an organisation, with nothing running on it. An IPv4 availability map is therefore not a map of what is free. It is a map of what is silent, and reading it means trusting silence only when you can prove it.
The three layers every map is built from
No single data source can tell you whether a block is usable. A useful map stacks three independent layers: - **Registry record** — who holds the block, since when, under which policy. This answers ownership, nothing else. - **BGP announcement** — whether the block is actually routed on the internet, and by whom. Unannounced space may be idle, or held for future use. - **Passive measurement** — whether anything responds to ordinary traffic: open ports, active services, DNS, mail servers. This layer detects life. Each layer answers a different question: who owns it, is it routed, is anything running? One layer alone tells you almost nothing. Two agreeing layers tell you something. Three disagreeing layers tell you the most.
The contradictions are the signal
The core reading rule: agreement between layers is background noise; contradiction is the signal. - Registered + announced + responding = normal use. Nothing to see. - Registered + announced + silent = routed but empty — or a firewall in front of everything. - Registered + not announced + silent = the candidate: it exists in the registry, nobody announces it, nothing responds. That is the definition of dormant space. The most valuable cells on any availability map are the last ones — where the registry says "exists" and the network says "nothing here". That contradiction is exactly what an inventory of dormant space is built from. And dormant space is the market's quiet supply: the **RIPE region — Europe and Türkiye — already carries the highest transfer volume in the world**, and much of it starts as registered-but-silent space like this.
The false positives, and how the map eliminates them
Silence is not always dormancy. Three common false positives: - **Firewalls.** A block that answers nothing may be fully active behind filtering. The map probes from multiple vantage points and looks for indirect signs — DNS records, TLS certificates, mail server configuration. - **Geographic filters.** Some networks only answer traffic from certain countries; cross-checking responses from different probe regions separates "geo-filtered" from "dead". - **Internal-only use.** Many blocks sit behind NAT and are used entirely inside a private network. They are genuinely silent on the internet, but not available — the registry record and a direct check with the holder settle it. A block that survives all three filters is not just silent; it is verifiably silent.
From map to inventory to offer
The flow that turns a map into revenue is short but deliberate: 1. **Map.** Generate the contradiction set: registered, unannounced, silent. 2. **Filter.** Remove the false positives until every surviving block is verifiably quiet. 3. **Inventory.** Rank the survivors — size, region, reputation, routability — and value them at market anchors: a /24 trades around **$27 per IP**, leasing runs about **$0.40 per IP per month**, and the cloud alternative costs roughly **$44 per address per year**. Those numbers turn a silent block into a balance-sheet figure. 4. **Reach out.** Most owners of dormant space never considered it an asset; one conversation with the inventory in hand is usually enough. 5. **Offer.** Lease for steady yield, or sell through a registry-approved transfer — both standard in the RIPE region's active transfer market.
The practical takeaway
An availability map is a decision tool, not a picture. Read the contradictions, eliminate the false positives, and you have a pipeline: silent block → verified inventory → offer. With AI, IoT and VPN operators driving demand and every free address already allocated, the market's remaining supply is hiding in the quiet space on the map. --- *Explore the IPDORM availability map and find registered-but-silent IPv4 space — [ipdorm.com](https://ipdorm.com).*