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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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 registered through ARIN
30,430 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 152.55.248.0/22 | 1k | ARIN |  US | 26th Feb 2026 |
| 152.55.252.0/22 | 1k | ARIN | US | 28th Apr 2026 |
| 152.64.0.0/16 | 65.5k | ARIN | US | 19th Aug 1991 |
| 152.68.0.0/16 | 65.5k | ARIN | US | 21st Aug 1991 |
| 153.14.0.0/16 | 65.5k | ARIN | US | 16th Sept 1991 |
| 153.16.0.0/16 | 65.5k | ARIN | US | 17th Sept 1991 |
| 153.30.0.0/16 | 65.5k | ARIN | US | 23rd Sept 1991 |
| 153.4.0.0/16 | 65.5k | ARIN | US | 12th Sept 1991 |
| 153.40.0.0/16 | 65.5k | ARIN | US | 3rd Jan 1992 |
| 153.50.0.0/16 | 65.5k | ARIN | US | 10th Jun 1992 |
| 153.52.128.0/19 | 8.2k | ARIN | US | 23rd Sept 1991 |
| 153.52.224.0/19 | 8.2k | ARIN | US | 5th Jun 2026 |
| 153.55.0.0/17 | 32.8k | ARIN | US | 23rd Sept 1991 |
| 153.55.192.0/18 | 16.4k | ARIN | US | 23rd Sept 1991 |
| 153.57.224.0/19 | 8.2k | ARIN | US | 10th Apr 2026 |
| 153.58.0.0/16 | 65.5k | ARIN | US | 23rd Sept 1991 |
| 153.60.64.0/18 | 16.4k | ARIN | US | 6th Apr 2026 |
| 153.62.0.0/16 | 65.5k | ARIN | US | 23rd Sept 1991 |
| 153.63.0.0/16 | 65.5k | ARIN | US | 23rd Sept 1991 |
| 153.70.0.0/15 | 131k | ARIN | US | 23rd Sept 1991 |
| 153.73.0.0/16 | 65.5k | ARIN | US | 23rd Sept 1991 |
| 153.74.0.0/16 | 65.5k | ARIN | US | 23rd Sept 1991 |
| 153.75.112.0/20 | 4.1k | ARIN | US | 6th May 2026 |
| 153.75.16.0/20 | 4.1k | ARIN | US | 24th Apr 2026 |
| 153.75.160.0/19 | 8.2k | ARIN | US | 23rd Sept 1991 |
| 153.75.96.0/20 | 4.1k | ARIN | US | 21st May 2026 |
| 153.76.128.0/19 | 8.2k | ARIN | US | 23rd Sept 1991 |
| 153.76.244.0/22 | 1k | ARIN | US | 23rd Sept 1991 |
| 153.78.0.0/16 | 65.5k | ARIN | US | 23rd Sept 1991 |
| 153.79.0.0/18 | 16.4k | ARIN | US | 23rd Sept 1991 |
| 153.79.160.0/21 | 2k | ARIN | US | 23rd Sept 1991 |
| 153.79.64.0/20 | 4.1k | ARIN | US | 23rd Sept 1991 |
| 153.79.96.0/20 | 4.1k | ARIN | US | 23rd Sept 1991 |
| 153.8.0.0/16 | 65.5k | ARIN | US | 12th Sept 1991 |
| 153.81.0.0/16 | 65.5k | ARIN | US | 23rd Sept 1991 |
| 153.82.0.0/15 | 131k | ARIN | US | 23rd Sept 1991 |
| 153.89.0.0/16 | 65.5k | ARIN |  BE | 23rd Sept 1991 |
| 154.15.0.0/16 | 65.5k | ARIN | US | 3rd Aug 2026 |
| 154.2.0.0/16 | 65.5k | ARIN | US | 5th Feb 1992 |
| 154.35.0.0/16 | 65.5k | ARIN | US | 5th Feb 1992 |
| 154.4.0.0/16 | 65.5k | ARIN | US | 5th Feb 1992 |
| 155.1.0.0/16 | 65.5k | ARIN | US | 30th Oct 1991 |
| 155.103.104.0/22 | 1k | ARIN | US | 13th Jan 2026 |
| 155.103.110.0/24 | 256 | ARIN | US | 13th Jan 2026 |
| 155.103.111.0/24 | 256 | ARIN | US | 13th Jan 2026 |
| 155.103.12.0/22 | 1k | ARIN | US | 2nd Apr 2026 |
| 155.103.126.0/23 | 512 | ARIN | US | 13th Jan 2026 |
| 155.103.136.0/22 | 1k | ARIN | US | 13th Jan 2026 |
| 155.103.148.0/22 | 1k | ARIN |  CA | 13th Jan 2026 |
| 155.103.16.0/22 | 1k | ARIN | US | 2nd Apr 2026 |