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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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 |
|---|---|---|---|---|
| 158.184.240.0/20 | 4.1k | ARIN |  US | 25th Mar 1992 |
| 158.184.32.0/19 | 8.2k | ARIN | US | 25th Mar 1992 |
| 158.184.4.0/22 | 1k | ARIN | US | 25th Mar 1992 |
| 158.184.64.0/19 | 8.2k | ARIN | US | 25th Mar 1992 |
| 158.184.8.0/21 | 2k | ARIN | US | 25th Mar 1992 |
| 158.184.96.0/21 | 2k | ARIN | US | 25th Mar 1992 |
| 158.185.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 158.186.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 158.187.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 158.188.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 158.189.0.0/16 | 65.5k | ARIN | US | 30th Mar 1992 |
| 158.21.0.0/16 | 65.5k | ARIN | US | 7th Feb 1992 |
| 158.22.0.0/16 | 65.5k | ARIN | US | 7th Feb 1992 |
| 158.222.44.0/22 | 1k | ARIN | US | 1st Apr 1992 |
| 158.247.48.0/21 | 2k | ARIN | US | 9th Jul 2020 |
| 158.247.62.0/23 | 512 | ARIN | US | 16th May 1991 |
| 158.247.64.0/23 | 512 | ARIN | US | 16th May 1991 |
| 158.247.66.0/23 | 512 | ARIN | US | 9th Jul 2020 |
| 158.25.0.0/16 | 65.5k | ARIN | US | 7th Feb 1992 |
| 158.27.0.0/16 | 65.5k | ARIN | US | 7th Feb 1992 |
| 158.29.0.0/16 | 65.5k | ARIN | US | 7th Feb 1992 |
| 158.30.0.0/16 | 65.5k | ARIN | US | 7th Feb 1992 |
| 158.31.0.0/16 | 65.5k | ARIN | US | 7th Feb 1992 |
| 158.32.0.0/16 | 65.5k | ARIN | US | 7th Feb 1992 |
| 158.33.0.0/16 | 65.5k | ARIN | US | 7th Feb 1992 |
| 158.34.0.0/16 | 65.5k | ARIN | US | 7th Feb 1992 |
| 158.51.0.0/23 | 512 | ARIN |  CA | 3rd Jan 2020 |
| 158.51.138.0/23 | 512 | ARIN | US | 10th Jan 2020 |
| 158.51.160.0/24 | 256 | ARIN | US | 22nd Jan 2020 |
| 158.51.201.0/24 | 256 | ARIN | US | 13th Jan 2023 |
| 158.51.202.0/24 | 256 | ARIN | US | 17th Jan 2020 |
| 158.51.232.0/22 | 1k | ARIN | US | 3rd Feb 2020 |
| 158.51.56.0/22 | 1k | ARIN | US | 3rd Jan 2020 |
| 158.51.90.0/24 | 256 | ARIN | US | 3rd Feb 2020 |
| 158.51.91.0/24 | 256 | ARIN | US | 3rd Apr 2025 |
| 158.55.0.0/16 | 65.5k | ARIN | US | 14th Feb 1992 |
| 158.76.0.0/16 | 65.5k | ARIN | US | 16th Feb 1992 |
| 158.77.0.0/16 | 65.5k | ARIN | US | 16th Feb 1992 |
| 158.78.0.0/16 | 65.5k | ARIN | US | 16th Feb 1992 |
| 158.82.0.0/16 | 65.5k | ARIN | US | 26th Feb 1992 |
| 158.84.0.0/16 | 65.5k | ARIN | US | 19th Feb 1992 |
| 158.98.0.0/16 | 65.5k | ARIN | US | 21st Feb 1992 |
| 159.102.0.0/16 | 65.5k | ARIN | US | 17th Mar 1992 |
| 159.127.44.0/22 | 1k | ARIN | US | 7th Oct 1996 |
| 159.127.48.0/20 | 4.1k | ARIN | US | 7th Oct 1996 |
| 159.129.0.0/16 | 65.5k | ARIN | US | 14th Apr 1992 |
| 159.131.0.0/16 | 65.5k | ARIN | US | 14th Apr 1992 |
| 159.132.0.0/16 | 65.5k | ARIN | US | 20th Apr 1992 |
| 159.139.0.0/16 | 65.5k | ARIN | US | 20th Apr 1992 |
| 159.161.0.0/16 | 65.5k | ARIN | US | 6th May 1992 |