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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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 |
|---|---|---|---|---|
| 168.151.156.0/24 | 256 | ARIN |  US | 6th Oct 2025 |
| 168.151.158.0/23 | 512 | ARIN | US | 4th Apr 1994 |
| 168.151.176.0/21 | 2k | ARIN | US | 4th Apr 1994 |
| 168.151.184.0/22 | 1k | ARIN | US | 4th Apr 1994 |
| 168.151.192.0/20 | 4.1k | ARIN | US | 4th Apr 1994 |
| 168.151.208.0/21 | 2k | ARIN | US | 4th Apr 1994 |
| 168.151.216.0/22 | 1k | ARIN | US | 4th Apr 1994 |
| 168.151.22.0/24 | 256 | ARIN | US | 6th Oct 2025 |
| 168.151.220.0/23 | 512 | ARIN | US | 4th Apr 1994 |
| 168.151.222.0/23 | 512 | ARIN | US | 3rd Oct 2025 |
| 168.151.224.0/22 | 1k | ARIN | US | 4th Apr 1994 |
| 168.151.228.0/23 | 512 | ARIN | US | 4th Apr 1994 |
| 168.151.23.0/24 | 256 | ARIN | US | 14th Jan 2019 |
| 168.151.24.0/24 | 256 | ARIN | US | 14th Oct 2025 |
| 168.151.240.0/21 | 2k | ARIN | US | 12th Jun 2026 |
| 168.151.248.0/22 | 1k | ARIN | US | 4th Apr 1994 |
| 168.151.252.0/23 | 512 | ARIN | US | 4th Apr 1994 |
| 168.151.32.0/21 | 2k | ARIN | US | 23rd Jun 2026 |
| 168.151.4.0/23 | 512 | ARIN | US | 4th Apr 1994 |
| 168.151.42.0/24 | 256 | ARIN | US | 5th Sept 2019 |
| 168.151.44.0/22 | 1k | ARIN | US | 4th Apr 1994 |
| 168.151.48.0/22 | 1k | ARIN | US | 4th Apr 1994 |
| 168.151.56.0/21 | 2k | ARIN | US | 4th Apr 1994 |
| 168.151.64.0/22 | 1k | ARIN | US | 17th Jul 2026 |
| 168.151.68.0/23 | 512 | ARIN | US | 4th Apr 1994 |
| 168.151.7.0/24 | 256 | ARIN | US | 17th Jan 2019 |
| 168.151.70.0/23 | 512 | ARIN | US | 6th Oct 2025 |
| 168.151.72.0/21 | 2k | ARIN | US | 4th Apr 1994 |
| 168.151.80.0/20 | 4.1k | ARIN | US | 4th Apr 1994 |
| 168.151.96.0/19 | 8.2k | ARIN | US | 4th Apr 1994 |
| 168.162.0.0/16 | 65.5k | ARIN | US | 23rd Aug 1994 |
| 168.192.0.0/15 | 131k | ARIN | US | 29th Sept 2022 |
| 168.204.0.0/16 | 65.5k | ARIN | US | 28th Jun 1994 |
| 168.207.0.0/16 | 65.5k | ARIN | US | 6th Jul 1994 |
| 168.213.128.0/18 | 16.4k | ARIN | US | 18th Jul 1994 |
| 168.213.192.0/19 | 8.2k | ARIN | US | 18th Jul 1994 |
| 168.213.224.0/20 | 4.1k | ARIN | US | 18th Jul 1994 |
| 168.213.240.0/21 | 2k | ARIN | US | 18th Jul 1994 |
| 168.213.248.0/22 | 1k | ARIN | US | 18th Jul 1994 |
| 168.213.252.0/24 | 256 | ARIN | US | 18th Jul 1994 |
| 168.220.64.0/20 | 4.1k | ARIN | US | 4th Aug 1994 |
| 168.237.0.0/16 | 65.5k | ARIN | US | 2nd Sept 1994 |
| 168.239.0.0/16 | 65.5k | ARIN | US | 7th Sept 1994 |
| 168.245.144.0/24 | 256 | ARIN | US | 23rd Mar 2021 |
| 168.245.156.0/24 | 256 | ARIN | US | 18th Sept 2018 |
| 168.245.194.0/24 | 256 | ARIN | US | 20th Jun 2017 |
| 168.245.204.0/24 | 256 | ARIN | US | 8th May 2017 |
| 168.245.216.0/21 | 2k | ARIN | US | 22nd May 2017 |
| 168.245.225.0/24 | 256 | ARIN | US | 15th Mar 2017 |
| 168.245.232.0/23 | 512 | ARIN | US | 18th Mar 2020 |