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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
84,968 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 131.143.78.0/24 | 256 | ARIN |  US | 7th Oct 2025 |
| 131.143.79.0/24 | 256 | ARIN | US | 7th Oct 2025 |
| 131.143.81.0/24 | 256 | ARIN | US | 10th Oct 2025 |
| 131.143.82.0/24 | 256 | ARIN |  CA | 17th Oct 2025 |
| 131.143.83.0/24 | 256 | ARIN | US | 10th Oct 2025 |
| 131.143.88.0/24 | 256 | ARIN | US | 8th Oct 2025 |
| 131.143.92.0/23 | 512 | ARIN | US | 7th Oct 2025 |
| 131.143.95.0/24 | 256 | ARIN | US | 7th Oct 2025 |
| 131.149.0.0/19 | 8.2k | ARIN | US | 27th Nov 2017 |
| 131.149.128.0/18 | 16.4k | ARIN | US | 27th Nov 2017 |
| 131.149.192.0/19 | 8.2k | ARIN | US | 27th Nov 2017 |
| 131.149.252.0/22 | 1k | ARIN | US | 27th Nov 2017 |
| 131.149.32.0/20 | 4.1k | ARIN | US | 27th Nov 2017 |
| 131.149.48.0/22 | 1k | ARIN | US | 27th Nov 2017 |
| 131.149.56.0/21 | 2k | ARIN | US | 27th Nov 2017 |
| 131.149.64.0/18 | 16.4k | ARIN | US | 27th Nov 2017 |
| 131.150.11.0/24 | 256 | ARIN | US | 23rd Nov 1988 |
| 131.150.12.0/22 | 1k | ARIN | US | 23rd Nov 1988 |
| 131.150.130.0/23 | 512 | ARIN | US | 23rd Nov 1988 |
| 131.150.144.0/20 | 4.1k | RIPE NCC |  NL | 15th May 2012 |
| 131.150.190.0/24 | 256 | ARIN | US | 23rd Nov 1988 |
| 131.150.31.0/24 | 256 | ARIN | US | 23rd Nov 1988 |
| 131.150.4.0/23 | 512 | ARIN | US | 27th Nov 2017 |
| 131.150.48.0/22 | 1k | ARIN | US | 27th Nov 2017 |
| 131.150.52.0/23 | 512 | ARIN | US | 27th Nov 2017 |
| 131.150.54.0/24 | 256 | ARIN | US | 27th Nov 2017 |
| 131.150.55.0/24 | 256 | ARIN | US | 23rd Nov 1988 |
| 131.150.56.0/22 | 1k | ARIN | US | 27th Nov 2017 |
| 131.150.6.0/24 | 256 | ARIN | US | 27th Nov 2017 |
| 131.150.60.0/23 | 512 | ARIN | US | 27th Nov 2017 |
| 131.150.62.0/24 | 256 | ARIN | US | 23rd Nov 1988 |
| 131.150.63.0/24 | 256 | ARIN | US | 27th Nov 2017 |
| 131.150.7.0/24 | 256 | ARIN | US | 23rd Nov 1988 |
| 131.150.8.0/23 | 512 | ARIN | US | 27th Nov 2017 |
| 131.150.80.0/22 | 1k | ARIN | US | 23rd Nov 1988 |
| 131.153.248.0/24 | 256 | ARIN | US | 16th Jan 2018 |
| 131.153.249.0/24 | 256 | ARIN | US | 13th Jan 2026 |
| 131.153.252.0/22 | 1k | ARIN | US | 20th Dec 2017 |
| 131.157.0.0/16 | 65.5k | ARIN | US | 6th Dec 1988 |
| 131.162.240.0/20 | 4.1k | ARIN | CA | 9th Dec 1988 |
| 131.185.0.0/16 | 65.5k | APNIC |  AU | 3rd Jan 1989 |
| 131.192.0.0/16 | 65.5k | ARIN | US | 4th Jan 1989 |
| 131.195.0.0/16 | 65.5k | ARIN | CA | 6th Jan 1989 |
| 131.205.0.0/16 | 65.5k | RIPE NCC |  SE | 11th Jan 1989 |
| 131.208.0.0/16 | 65.5k | ARIN | US | 16th Jan 1989 |
| 131.209.0.0/16 | 65.5k | ARIN | US | 16th Jan 1989 |
| 131.221.152.0/22 | 1k | LACNIC |  BR | 30th Apr 2026 |
| 131.221.28.0/22 | 1k | LACNIC |  TT | 22nd Oct 2014 |
| 131.222.0.0/17 | 32.8k | RIPE NCC |  AE | 6th Apr 1990 |
| 131.222.132.0/24 | 256 | RIPE NCC |  TR | 6th Apr 1990 |