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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
26,249 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 173.225.64.0/21 | 2k | ARIN |  US | 28th Jan 2010 |
| 173.228.160.0/19 | 8.2k | ARIN | US | 11th Jul 2018 |
| 173.230.192.0/19 | 8.2k | ARIN | US | 22nd Mar 2010 |
| 173.234.192.0/21 | 2k | ARIN | US | 12th Feb 2010 |
| 173.241.240.0/20 | 4.1k | ARIN | US | 30th Apr 2010 |
| 173.242.32.0/20 | 4.1k | ARIN | US | 5th May 2010 |
| 173.243.156.0/22 | 1k | ARIN | US | 3rd Jun 2010 |
| 173.243.232.0/22 | 1k | ARIN | US | 29th Oct 2025 |
| 173.244.64.0/20 | 4.1k | ARIN | US | 23rd Apr 2010 |
| 173.245.0.0/19 | 8.2k | ARIN | US | 11th May 2010 |
| 173.245.176.0/20 | 4.1k | ARIN | US | 20th May 2010 |
| 173.249.80.0/20 | 4.1k | ARIN | US | 30th May 2018 |
| 173.255.128.0/20 | 4.1k | ARIN | US | 30th Aug 2011 |
| 173.4.0.0/14 | 262k | ARIN | US | 30th Apr 2008 |
| 174.124.0.0/15 | 131k | ARIN | US | 7th Apr 2009 |
| 174.128.200.0/22 | 1k | ARIN | US | 4th Jun 2026 |
| 174.128.216.0/21 | 2k | ARIN | US | 1st Jul 2010 |
| 174.139.0.0/16 | 65.5k | ARIN | US | 11th Nov 2008 |
| 174.34.233.0/24 | 256 | ARIN | US | 22nd Sept 2020 |
| 174.34.255.0/24 | 256 | ARIN | US | 18th Apr 2019 |
| 174.8.0.0/13 | 524k | ARIN | US | 7th Jan 2009 |
| 179.197.0.0/18 | 16.4k | ARIN | US | 20th Feb 2025 |
| 184.128.0.0/12 | 1M | ARIN | US | 25th Feb 2010 |
| 184.170.144.0/20 | 4.1k | ARIN | US | 18th May 2011 |
| 184.172.0.0/15 | 131k | ARIN | US | 6th Oct 2010 |
| 184.88.0.0/14 | 262k | ARIN | US | 31st Mar 2010 |
| 184.95.16.0/20 | 4.1k | ARIN | US | 14th Aug 2024 |
| 185.144.68.0/23 | 512 | ARIN | US | 19th Sept 2024 |
| 185.20.220.0/22 | 1k | ARIN | US | 11th May 2017 |
| 185.203.207.0/24 | 256 | ARIN | US | 11th Apr 2022 |
| 185.39.52.0/22 | 1k | ARIN | US | 22nd Jun 2020 |
| 185.74.168.0/22 | 1k | ARIN | US | 4th Apr 2022 |
| 185.77.4.0/23 | 512 | ARIN | US | 13th Feb 2020 |
| 185.77.6.0/23 | 512 | ARIN | US | 15th Apr 2019 |
| 185.81.136.0/22 | 1k | ARIN | US | 22nd Jun 2020 |
| 185.90.244.0/22 | 1k | ARIN | US | 15th Jun 2017 |
| 187.13.32.0/20 | 4.1k | ARIN | US | 13th Mar 2025 |
| 187.42.192.0/18 | 16.4k | ARIN | US | 20th Feb 2025 |
| 188.209.144.0/21 | 2k | ARIN | US | 23rd Jul 2018 |
| 190.2.190.0/24 | 256 | ARIN | US | 26th May 2026 |
| 191.45.64.0/18 | 16.4k | ARIN | US | 24th Apr 2026 |
| 192.100.10.0/24 | 256 | ARIN | US | 12th Mar 1991 |
| 192.100.11.0/24 | 256 | ARIN | US | 12th Mar 1991 |
| 192.100.12.0/24 | 256 | ARIN | US | 12th Mar 1991 |
| 192.100.13.0/24 | 256 | ARIN | US | 12th Mar 1991 |
| 192.100.141.0/24 | 256 | ARIN | US | 15th Apr 1991 |
| 192.100.142.0/24 | 256 | ARIN | US | 15th Apr 1991 |
| 192.100.145.0/24 | 256 | ARIN | US | 17th Apr 1991 |
| 192.100.146.0/24 | 256 | ARIN | US | 17th Apr 1991 |
| 192.100.147.0/24 | 256 | ARIN | US | 22nd Apr 1991 |