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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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 registered through ARIN
30,434 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 172.96.36.0/23 | 512 | ARIN |  US | 14th Mar 2025 |
| 172.96.40.0/21 | 2k | ARIN |  CA | 9th Jun 2015 |
| 172.97.112.0/22 | 1k | ARIN | US | 15th Jul 2015 |
| 172.97.60.0/22 | 1k | ARIN | CA | 12th Jun 2015 |
| 172.98.25.0/24 | 256 | ARIN | US | 15th Jul 2021 |
| 172.98.28.0/24 | 256 | ARIN | US | 11th Oct 2023 |
| 172.98.40.0/22 | 1k | ARIN | US | 7th Jul 2021 |
| 172.98.5.0/24 | 256 | ARIN | US | 13th Jan 2026 |
| 172.98.6.0/24 | 256 | ARIN | US | 7th Jul 2021 |
| 172.98.7.0/24 | 256 | ARIN | US | 12th Jul 2021 |
| 172.99.140.0/22 | 1k | ARIN | US | 11th Jan 2021 |
| 172.99.162.0/23 | 512 | ARIN | US | 11th Jan 2021 |
| 172.99.164.0/22 | 1k | ARIN | CA | 13th Jan 2021 |
| 172.99.234.0/23 | 512 | ARIN | US | 15th Feb 2021 |
| 172.99.244.0/23 | 512 | ARIN | US | 6th Jan 2021 |
| 172.99.248.0/24 | 256 | ARIN | US | 13th Jan 2021 |
| 173.195.107.0/24 | 256 | ARIN | US | 30th Aug 2019 |
| 173.195.112.0/20 | 4.1k | ARIN | US | 15th Sept 2010 |
| 173.195.32.0/20 | 4.1k | ARIN | US | 25th Jul 2024 |
| 173.205.206.0/23 | 512 | ARIN | US | 22nd Jan 2020 |
| 173.208.62.0/23 | 512 | ARIN | US | 17th Dec 2009 |
| 173.209.80.0/20 | 4.1k | ARIN | US | 28th Oct 2010 |
| 173.214.204.0/24 | 256 | ARIN | US | 20th Dec 2018 |
| 173.214.205.0/24 | 256 | ARIN | US | 7th Oct 2020 |
| 173.214.208.0/22 | 1k | ARIN | US | 7th Apr 2025 |
| 173.214.212.0/22 | 1k | ARIN | CA | 14th Apr 2025 |
| 173.214.220.0/23 | 512 | ARIN | US | 3rd Apr 2025 |
| 173.214.222.0/23 | 512 | ARIN | US | 3rd Apr 2025 |
| 173.224.168.0/23 | 512 | ARIN | US | 18th Jul 2012 |
| 173.224.224.0/20 | 4.1k | ARIN | CA | 22nd Jan 2010 |
| 173.225.64.0/21 | 2k | ARIN | US | 28th Jan 2010 |
| 173.225.72.0/21 | 2k | ARIN |  PR | 28th Jan 2025 |
| 173.228.160.0/19 | 8.2k | ARIN | US | 11th Jul 2018 |
| 173.230.192.0/19 | 8.2k | ARIN | US | 22nd Mar 2010 |
| 173.241.240.0/20 | 4.1k | ARIN | US | 30th Apr 2010 |
| 173.242.32.0/20 | 4.1k | ARIN | US | 5th May 2010 |
| 173.243.232.0/22 | 1k | ARIN | US | 29th Oct 2025 |
| 173.243.48.0/20 | 4.1k | ARIN | CA | 21st May 2010 |
| 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 |
| 173.249.164.0/22 | 1k | ARIN | US | 4th Oct 2021 |
| 173.249.80.0/20 | 4.1k | ARIN | US | 30th May 2018 |
| 173.250.0.0/17 | 32.8k | ARIN | CA | 1st Jun 2010 |
| 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 |
| 174.128.204.0/22 | 1k | ARIN | US | 1st Jul 2010 |
| 174.136.112.0/20 | 4.1k | ARIN | CA | 18th Nov 2010 |
| 174.136.240.0/22 | 1k | ARIN | CA | 1st Apr 2024 |