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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
26,273 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 104.224.40.0/23 | 512 | ARIN |  US | 4th Jan 2021 |
| 104.225.135.0/24 | 256 | ARIN | US | 24th Feb 2025 |
| 104.225.136.0/22 | 1k | ARIN | US | 17th Oct 2017 |
| 104.225.214.0/24 | 256 | ARIN | US | 26th Apr 2017 |
| 104.232.8.0/24 | 256 | ARIN | US | 13th Feb 2020 |
| 104.237.80.0/20 | 4.1k | ARIN | US | 11th Nov 2014 |
| 104.238.196.0/24 | 256 | ARIN | US | 3rd Apr 2025 |
| 104.238.210.0/23 | 512 | ARIN | US | 19th Nov 2024 |
| 104.238.226.0/24 | 256 | ARIN | US | 19th Aug 2019 |
| 104.238.227.0/24 | 256 | ARIN | US | 17th Oct 2019 |
| 104.238.237.0/24 | 256 | ARIN | US | 7th Dec 2024 |
| 104.238.240.0/21 | 2k | ARIN | US | 28th Aug 2017 |
| 104.242.224.0/19 | 8.2k | ARIN | US | 27th Apr 2022 |
| 104.244.184.0/22 | 1k | ARIN | US | 18th Nov 2014 |
| 104.244.200.0/21 | 2k | ARIN | US | 5th Jan 2015 |
| 104.244.36.0/22 | 1k | ARIN | US | 11th Nov 2014 |
| 104.244.80.0/22 | 1k | ARIN | US | 14th Nov 2014 |
| 104.245.124.0/22 | 1k | ARIN | US | 9th Dec 2014 |
| 104.245.140.0/22 | 1k | ARIN | US | 9th Dec 2014 |
| 104.245.176.0/22 | 1k | ARIN | US | 15th Dec 2014 |
| 104.247.0.0/19 | 8.2k | ARIN | US | 24th Dec 2014 |
| 104.247.124.0/24 | 256 | ARIN | US | 8th Jul 2021 |
| 104.247.125.0/24 | 256 | ARIN | US | 19th Jul 2021 |
| 104.247.93.0/24 | 256 | ARIN | US | 29th Jun 2016 |
| 104.247.94.0/23 | 512 | ARIN | US | 29th Jun 2016 |
| 104.247.99.0/24 | 256 | ARIN | US | 13th Jan 2026 |
| 104.249.134.0/24 | 256 | ARIN | US | 7th Apr 2021 |
| 104.249.135.0/24 | 256 | ARIN | US | 26th Apr 2021 |
| 104.249.169.0/24 | 256 | ARIN | US | 12th Apr 2021 |
| 104.250.228.0/24 | 256 | ARIN | US | 2nd Jul 2021 |
| 104.250.231.0/24 | 256 | ARIN | US | 1st Jul 2021 |
| 104.250.240.0/22 | 1k | ARIN | US | 1st Jul 2021 |
| 104.251.192.0/20 | 4.1k | ARIN | US | 29th Dec 2014 |
| 104.254.112.0/21 | 2k | ARIN | US | 2nd Jan 2015 |
| 104.254.132.0/22 | 1k | ARIN | US | 23rd Jan 2015 |
| 104.254.24.0/21 | 2k | ARIN | US | 23rd Dec 2014 |
| 104.255.120.0/22 | 1k | ARIN | US | 28th Jan 2015 |
| 104.255.136.0/22 | 1k | ARIN | US | 28th Sept 2016 |
| 104.255.216.0/22 | 1k | ARIN | US | 4th Feb 2015 |
| 104.255.34.0/24 | 256 | ARIN | US | 22nd Aug 2018 |
| 104.36.144.0/22 | 1k | ARIN | US | 3rd Jun 2014 |
| 104.36.204.0/22 | 1k | ARIN | US | 6th Jun 2014 |
| 104.36.51.0/24 | 256 | ARIN | US | 28th Mar 2025 |
| 104.37.116.0/22 | 1k | ARIN | US | 23rd Jun 2014 |
| 104.37.168.0/22 | 1k | ARIN | US | 18th Jun 2014 |
| 104.37.48.0/22 | 1k | ARIN | US | 25th Apr 2024 |
| 104.37.8.0/21 | 2k | ARIN | US | 9th Apr 2025 |
| 107.150.136.0/23 | 512 | ARIN | US | 13th Dec 2013 |
| 107.152.16.0/20 | 4.1k | ARIN | US | 27th Nov 2013 |
| 107.155.160.0/20 | 4.1k | ARIN | US | 13th Oct 2022 |