Allocated but unannounced space
Every block here was allocated or assigned by a regional internet registry, and none of them appeared in any routing table we collected at our last snapshot — neither as a route of their own, nor covered by a larger announcement, nor carved up into more specifics.
“Unannounced” does not mean “unused”
Plenty of allocated space is deliberately kept off the public internet: private interconnects, lab and lawful-intercept ranges, networks reachable only inside one operator, and space held in reserve. Some of it is announced somewhere our collectors cannot see, which is a limit of our vantage points rather than a fact about the block.
It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today. Nothing on this page means a block is unallocated, available, or free to announce.
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Countries with unannounced space registered through ARIN, largest first.
Unannounced blocks in United States
26,251 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 2631:a000::/24 | 1.1T × /64 | ARIN |  US | 11th May 2026 |
| 31.220.216.0/21 | 2k | ARIN | US | 4th Dec 2024 |
| 31.220.245.0/24 | 256 | ARIN | US | 4th Dec 2024 |
| 31.99.128.0/20 | 4.1k | ARIN | US | 18th May 2026 |
| 31.99.152.0/24 | 256 | ARIN | US | 18th May 2026 |
| 32.144.0.0/12 | 1M | ARIN | US | 25th Sept 2023 |
| 32.240.0.0/15 | 131k | ARIN | US | 23rd Jun 2023 |
| 34.3.2.0/24 | 256 | ARIN | US | 9th May 2022 |
| 35.128.216.0/21 | 2k | ARIN | US | 1st Apr 1994 |
| 35.128.224.0/19 | 8.2k | ARIN | US | 1st Apr 1994 |
| 35.18.0.0/15 | 131k | ARIN | US | 8th Feb 2024 |
| 35.26.0.0/15 | 131k | ARIN | US | 8th Feb 2024 |
| 35.28.0.0/14 | 262k | ARIN | US | 8th Feb 2024 |
| 35.34.64.0/20 | 4.1k | ARIN | US | 1st Apr 1994 |
| 35.48.0.0/15 | 131k | ARIN | US | 8th Feb 2024 |
| 35.52.0.0/15 | 131k | ARIN | US | 8th Feb 2024 |
| 35.56.0.0/15 | 131k | ARIN | US | 8th Feb 2024 |
| 35.60.0.0/15 | 131k | ARIN | US | 8th Feb 2024 |
| 36.2.112.0/20 | 4.1k | ARIN | US | 26th Jun 2024 |
| 36.2.128.0/20 | 4.1k | ARIN | US | 26th Jun 2024 |
| 36.2.224.0/20 | 4.1k | ARIN | US | 26th Jun 2024 |
| 36.2.32.0/20 | 4.1k | ARIN | US | 26th Jun 2024 |
| 36.3.80.0/20 | 4.1k | ARIN | US | 26th Jun 2024 |
| 37.128.192.0/21 | 2k | ARIN | US | 22nd May 2024 |
| 4.128.0.0/12 | 1M | ARIN | US | 17th Jul 2019 |
| 40.149.0.0/16 | 65.5k | ARIN | US | 23rd Apr 1991 |
| 40.150.0.0/16 | 65.5k | ARIN | US | 4th Dec 2023 |
| 40.152.0.0/15 | 131k | ARIN | US | 23rd Apr 1991 |
| 40.154.0.0/16 | 65.5k | ARIN | US | 23rd Apr 1991 |
| 40.158.0.0/16 | 65.5k | ARIN | US | 23rd Apr 1991 |
| 40.16.0.0/16 | 65.5k | ARIN | US | 23rd Apr 1991 |
| 40.163.0.0/16 | 65.5k | ARIN | US | 18th Feb 2022 |
| 40.18.0.0/15 | 131k | ARIN | US | 23rd Apr 1991 |
| 40.186.0.0/15 | 131k | ARIN | US | 4th Dec 2023 |
| 40.189.0.0/16 | 65.5k | ARIN | US | 23rd Apr 1991 |
| 40.194.0.0/16 | 65.5k | ARIN | US | 16th Jun 2023 |
| 40.195.0.0/16 | 65.5k | ARIN | US | 21st Oct 2022 |
| 40.20.0.0/16 | 65.5k | ARIN | US | 23rd Apr 1991 |
| 40.202.0.0/16 | 65.5k | ARIN | US | 23rd Apr 1991 |
| 40.203.0.0/16 | 65.5k | ARIN | US | 13th Feb 2023 |
| 40.211.0.0/16 | 65.5k | ARIN | US | 23rd Apr 1991 |
| 40.215.0.0/16 | 65.5k | ARIN | US | 23rd Apr 1991 |
| 40.217.0.0/16 | 65.5k | ARIN | US | 13th Feb 2023 |
| 40.219.0.0/16 | 65.5k | ARIN | US | 13th Feb 2023 |
| 40.22.0.0/15 | 131k | ARIN | US | 23rd Apr 1991 |
| 40.221.0.0/16 | 65.5k | ARIN | US | 13th Feb 2023 |
| 40.222.0.0/16 | 65.5k | ARIN | US | 13th Feb 2023 |
| 40.225.0.0/16 | 65.5k | ARIN | US | 23rd Apr 1991 |
| 40.230.0.0/16 | 65.5k | ARIN | US | 13th Feb 2023 |
| 40.233.128.0/17 | 32.8k | ARIN | US | 23rd Apr 1991 |