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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
Browse by country
Countries with the most unannounced blocks, largest first.
Unannounced blocks
84,619 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 66.151.168.0/21 | 2k | ARIN |  US | 13th Jul 2001 |
| 66.151.212.0/22 | 1k | ARIN | US | 13th Jul 2001 |
| 66.151.56.0/21 | 2k | ARIN | US | 13th Jul 2001 |
| 66.155.64.0/22 | 1k | RIPE NCC | US | 27th Jul 2001 |
| 66.159.0.0/19 | 8.2k | ARIN | US | 16th Jul 2002 |
| 66.163.208.0/24 | 256 | ARIN | US | 28th Apr 2014 |
| 66.163.210.0/23 | 512 | ARIN | US | 28th Apr 2014 |
| 66.163.215.0/24 | 256 | ARIN | US | 28th Apr 2014 |
| 66.163.216.0/24 | 256 | ARIN | US | 28th Apr 2014 |
| 66.163.220.0/24 | 256 | ARIN | US | 25th Apr 2024 |
| 66.163.222.0/24 | 256 | ARIN | US | 28th Apr 2014 |
| 66.163.223.0/24 | 256 | ARIN | US | 20th Nov 2024 |
| 66.170.112.0/20 | 4.1k | ARIN | US | 18th Aug 2003 |
| 66.171.32.0/23 | 512 | ARIN | US | 12th Feb 2016 |
| 66.171.38.0/24 | 256 | ARIN | US | 1st Oct 2026 |
| 66.171.39.0/24 | 256 | ARIN | US | 28th May 2026 |
| 66.179.103.0/24 | 256 | ARIN | US | 3rd May 2024 |
| 66.179.120.0/21 | 2k | ARIN | US | 9th Oct 2001 |
| 66.179.144.0/22 | 1k | ARIN | US | 16th Jan 2024 |
| 66.179.162.0/23 | 512 | ARIN | US | 9th Oct 2001 |
| 66.179.164.0/23 | 512 | ARIN | US | 9th Oct 2001 |
| 66.179.169.0/24 | 256 | RIPE NCC | US | 9th Oct 2001 |
| 66.179.170.0/23 | 512 | ARIN | US | 3rd Aug 2026 |
| 66.179.172.0/23 | 512 | ARIN | US | 9th Oct 2001 |
| 66.179.174.0/24 | 256 | RIPE NCC | US | 9th Oct 2001 |
| 66.179.180.0/22 | 1k | ARIN | US | 19th Jan 2024 |
| 66.179.184.0/22 | 1k | ARIN | US | 9th Oct 2001 |
| 66.179.200.0/23 | 512 | ARIN | US | 17th Jul 2024 |
| 66.179.22.0/24 | 256 | ARIN | US | 21st Jul 2023 |
| 66.179.24.0/22 | 1k | ARIN | US | 9th Oct 2001 |
| 66.179.28.0/24 | 256 | ARIN | US | 9th Oct 2001 |
| 66.179.32.0/22 | 1k | ARIN | US | 9th Oct 2001 |
| 66.179.38.0/23 | 512 | ARIN | US | 24th Jul 2024 |
| 66.180.208.0/20 | 4.1k | ARIN | US | 9th May 2006 |
| 66.180.64.0/24 | 256 | ARIN | US | 30th Sept 2016 |
| 66.180.68.0/22 | 1k | ARIN |  CA | 19th Dec 2016 |
| 66.181.96.0/20 | 4.1k | ARIN | US | 24th Oct 2001 |
| 66.182.96.0/20 | 4.1k | ARIN | US | 26th Mar 2024 |
| 66.186.112.0/20 | 4.1k | ARIN | US | 10th Jan 2006 |
| 66.186.194.0/23 | 512 | RIPE NCC |  AL | 9th Nov 2001 |
| 66.187.14.0/24 | 256 | ARIN | CA | 26th Dec 2024 |
| 66.187.3.0/24 | 256 | ARIN | US | 27th Apr 2021 |
| 66.196.128.0/18 | 16.4k | ARIN | US | 22nd Jul 2020 |
| 66.203.250.0/24 | 256 | ARIN | US | 4th Dec 2025 |
| 66.203.251.0/24 | 256 | ARIN | US | 15th Jan 2026 |
| 66.205.228.0/22 | 1k | ARIN | US | 26th Sept 2019 |
| 66.205.234.0/24 | 256 | ARIN | US | 9th Sept 2019 |
| 66.206.208.0/20 | 4.1k | ARIN | US | 16th Jun 2008 |
| 66.206.64.0/20 | 4.1k | ARIN | US | 7th Dec 2001 |
| 66.207.48.0/23 | 512 | ARIN | US | 22nd Mar 2024 |