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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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.
Browse by registry
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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 |
|---|---|---|---|---|
| 192.157.38.0/24 | 256 | ARIN |  US | 16th Apr 1992 |
| 192.157.4.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.157.6.0/23 | 512 | ARIN | US | 4th Mar 2015 |
| 192.157.96.0/19 | 8.2k | ARIN |  CA | 28th Jun 2013 |
| 192.158.1.0/24 | 256 | ARIN | US | 20th Apr 1992 |
| 192.158.104.0/22 | 1k | ARIN | US | 21st Apr 1992 |
| 192.158.108.0/24 | 256 | ARIN | US | 22nd Apr 2026 |
| 192.158.109.0/24 | 256 | ARIN | US | 21st Apr 1992 |
| 192.158.112.0/22 | 1k | ARIN | US | 21st Apr 1992 |
| 192.158.116.0/23 | 512 | ARIN | US | 21st Apr 1992 |
| 192.158.120.0/21 | 2k | ARIN | US | 21st Apr 1992 |
| 192.158.128.0/21 | 2k | ARIN | US | 21st Apr 1992 |
| 192.158.136.0/22 | 1k | ARIN | US | 21st Apr 1992 |
| 192.158.142.0/24 | 256 | ARIN | US | 21st Apr 1992 |
| 192.158.144.0/20 | 4.1k | ARIN | US | 21st Apr 1992 |
| 192.158.160.0/20 | 4.1k | ARIN | US | 12th Nov 2026 |
| 192.158.176.0/21 | 2k | ARIN | US | 21st Apr 1992 |
| 192.158.18.0/24 | 256 | ARIN | US | 29th Apr 1992 |
| 192.158.184.0/22 | 1k | ARIN | US | 21st Apr 1992 |
| 192.158.188.0/23 | 512 | ARIN | US | 21st Apr 1992 |
| 192.158.190.0/23 | 512 | ARIN | US | 16th Jul 2026 |
| 192.158.192.0/21 | 2k | ARIN | US | 21st Apr 1992 |
| 192.158.2.0/24 | 256 | ARIN | US | 20th Apr 1992 |
| 192.158.20.0/24 | 256 | ARIN | US | 29th Apr 1992 |
| 192.158.200.0/22 | 1k | ARIN | US | 21st Apr 1992 |
| 192.158.204.0/22 | 1k | ARIN | US | 23rd Apr 1992 |
| 192.158.208.0/22 | 1k | ARIN | US | 23rd Apr 1992 |
| 192.158.21.0/24 | 256 | ARIN | US | 29th Apr 1992 |
| 192.158.212.0/23 | 512 | ARIN | US | 23rd Apr 1992 |
| 192.158.22.0/24 | 256 | ARIN | US | 29th Apr 1992 |
| 192.158.23.0/24 | 256 | ARIN | US | 29th Apr 1992 |
| 192.158.24.0/24 | 256 | ARIN | US | 29th Apr 1992 |
| 192.158.25.0/24 | 256 | ARIN | US | 2nd Jul 2015 |
| 192.158.254.0/24 | 256 | ARIN | US | 26th May 1992 |
| 192.158.32.0/24 | 256 | ARIN | US | 4th May 1992 |
| 192.158.38.0/24 | 256 | ARIN | US | 4th May 1992 |
| 192.158.39.0/24 | 256 | ARIN | US | 4th May 1992 |
| 192.158.40.0/24 | 256 | ARIN | US | 4th May 1992 |
| 192.158.41.0/24 | 256 | ARIN | US | 4th May 1992 |
| 192.158.43.0/24 | 256 | ARIN | US | 4th May 1992 |
| 192.158.46.0/24 | 256 | ARIN | US | 4th May 1992 |
| 192.158.47.0/24 | 256 | ARIN | US | 4th May 1992 |
| 192.158.48.0/24 | 256 | ARIN | US | 4th May 1992 |
| 192.158.49.0/24 | 256 | ARIN | US | 4th May 1992 |
| 192.158.50.0/24 | 256 | ARIN | US | 4th May 1992 |
| 192.158.51.0/24 | 256 | ARIN | US | 4th May 1992 |
| 192.158.52.0/24 | 256 | ARIN | US | 4th May 1992 |
| 192.158.53.0/24 | 256 | ARIN | US | 4th May 1992 |
| 192.158.56.0/24 | 256 | ARIN | US | 4th May 1992 |
| 192.158.57.0/24 | 256 | ARIN | US | 4th May 1992 |