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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
26,277 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 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 |
| 40.163.0.0/16 | 65.5k | ARIN | US | 18th Feb 2022 |
| 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 |
| 40.238.0.0/16 | 65.5k | ARIN | US | 4th Dec 2023 |
| 40.239.0.0/16 | 65.5k | ARIN | US | 28th Sept 2022 |
| 40.24.0.0/16 | 65.5k | ARIN | US | 23rd Apr 1991 |
| 40.240.0.0/16 | 65.5k | ARIN | US | 23rd Apr 1991 |
| 40.241.0.0/16 | 65.5k | ARIN | US | 28th Jul 2022 |
| 40.242.0.0/16 | 65.5k | ARIN | US | 28th Jul 2022 |
| 40.243.0.0/16 | 65.5k | ARIN | US | 23rd Apr 1991 |
| 40.244.0.0/14 | 262k | ARIN | US | 23rd Apr 1991 |
| 40.26.0.0/16 | 65.5k | ARIN | US | 23rd Apr 1991 |
| 40.36.0.0/15 | 131k | ARIN | US | 23rd Apr 1991 |
| 40.40.0.0/14 | 262k | ARIN | US | 23rd Apr 1991 |
| 40.57.0.0/16 | 65.5k | ARIN | US | 23rd Apr 1991 |
| 45.0.0.0/15 | 131k | ARIN | US | 9th Sept 1991 |
| 45.150.52.0/22 | 1k | ARIN | US | 21st Jan 2025 |
| 45.154.219.0/24 | 256 | ARIN | US | 11th Apr 2022 |
| 45.159.108.0/24 | 256 | ARIN | US | 13th Oct 2025 |
| 45.33.194.0/24 | 256 | ARIN | US | 19th Nov 2020 |
| 45.33.197.0/24 | 256 | ARIN | US | 5th Mar 2019 |
| 45.34.0.0/15 | 131k | ARIN | US | 6th Dec 2023 |
| 45.40.16.0/20 | 4.1k | ARIN | US | 26th Feb 2015 |