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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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 in United States
26,972 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 172.87.231.0/24 | 256 | ARIN |  US | 1st Jul 2025 |
| 172.87.240.0/20 | 4.1k | ARIN | US | 29th Nov 2017 |
| 172.96.130.0/23 | 512 | ARIN | US | 1st May 2018 |
| 172.96.36.0/23 | 512 | ARIN | US | 14th Mar 2025 |
| 172.97.112.0/22 | 1k | ARIN | US | 15th Jul 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 |
| 172.99.234.0/23 | 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 |
| 173.214.220.0/23 | 512 | ARIN | US | 3rd Apr 2025 |
| 173.214.222.0/23 | 512 | ARIN | US | 3rd Apr 2025 |
| 173.214.32.0/19 | 8.2k | ARIN | US | 2nd Nov 2026 |
| 173.214.64.0/19 | 8.2k | ARIN | US | 3rd Nov 2026 |
| 173.214.96.0/20 | 4.1k | ARIN | US | 29th Oct 2026 |
| 173.224.168.0/23 | 512 | ARIN | US | 18th Jul 2012 |
| 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 |