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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
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Countries with the most unannounced blocks, largest first.
Unannounced blocks in United States
26,971 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 136.23.128.0/17 | 32.8k | ARIN |  US | 1st Aug 2024 |
| 136.237.0.0/16 | 65.5k | ARIN | US | 3rd Oct 1989 |
| 136.240.0.0/15 | 131k | ARIN | US | 5th Oct 1989 |
| 136.242.128.0/17 | 32.8k | RIPE NCC | US | 5th Oct 1989 |
| 136.242.80.0/23 | 512 | ARIN | US | 12th Jun 2025 |
| 136.245.144.0/20 | 4.1k | ARIN | US | 5th Oct 1989 |
| 136.245.160.0/19 | 8.2k | ARIN | US | 5th Oct 1989 |
| 136.245.192.0/18 | 16.4k | ARIN | US | 5th Oct 1989 |
| 136.8.0.0/15 | 131k | ARIN | US | 29th Nov 2021 |
| 136.96.0.0/13 | 524k | ARIN | US | 1st Aug 2024 |
| 137.102.0.0/16 | 65.5k | ARIN | US | 15th Nov 1989 |
| 137.136.0.0/16 | 65.5k | ARIN | US | 29th Nov 1989 |
| 137.137.0.0/16 | 65.5k | ARIN | US | 29th Nov 1989 |
| 137.167.0.0/16 | 65.5k | ARIN | US | 18th Dec 1989 |
| 137.168.0.0/16 | 65.5k | ARIN | US | 13th Dec 1989 |
| 137.173.0.0/16 | 65.5k | ARIN | US | 13th Dec 1989 |
| 137.197.0.0/16 | 65.5k | ARIN | US | 3rd Jan 1989 |
| 137.199.0.0/16 | 65.5k | ARIN | US | 3rd Jan 1990 |
| 137.20.0.0/16 | 65.5k | ARIN | US | 11th Oct 1989 |
| 137.206.0.0/16 | 65.5k | ARIN | US | 3rd Jan 1990 |
| 137.212.0.0/16 | 65.5k | ARIN | US | 9th Jan 1990 |
| 137.239.128.0/19 | 8.2k | ARIN | US | 16th Jan 1990 |
| 137.245.0.0/16 | 65.5k | ARIN | US | 16th Jan 1990 |
| 137.249.0.0/16 | 65.5k | ARIN | US | 20th Jan 1990 |
| 137.252.0.0/16 | 65.5k | ARIN | US | 26th Oct 2016 |
| 137.254.0.0/16 | 65.5k | ARIN | US | 17th Jan 1990 |
| 137.29.0.0/16 | 65.5k | ARIN | US | 19th Oct 1989 |
| 137.38.0.0/16 | 65.5k | ARIN | US | 25th Oct 1989 |
| 137.41.0.0/16 | 65.5k | ARIN | US | 2nd Jun 1997 |
| 137.42.0.0/16 | 65.5k | ARIN | US | 25th Oct 1989 |
| 137.46.0.0/16 | 65.5k | ARIN | US | 2nd Nov 1989 |
| 137.49.128.0/18 | 16.4k | ARIN | US | 1st Nov 1989 |
| 137.49.192.0/19 | 8.2k | ARIN | US | 1st Nov 1989 |
| 137.57.0.0/16 | 65.5k | ARIN | US | 5th Jul 1990 |
| 137.72.0.0/16 | 65.5k | ARIN | US | 6th Nov 1989 |
| 137.83.1.0/24 | 256 | ARIN | US | 9th Aug 2019 |
| 137.83.11.0/24 | 256 | ARIN | US | 26th Jun 2019 |
| 137.83.26.0/24 | 256 | ARIN | US | 28th Jan 2020 |
| 137.83.38.0/23 | 512 | ARIN | US | 23rd Oct 2020 |
| 137.83.58.0/23 | 512 | ARIN | US | 28th Jan 2019 |
| 137.83.73.0/24 | 256 | ARIN | US | 7th Apr 2020 |
| 137.83.78.0/24 | 256 | ARIN | US | 16th Apr 2020 |
| 137.83.88.0/24 | 256 | ARIN | US | 28th Jan 2026 |
| 138.112.0.0/16 | 65.5k | ARIN | US | 1st May 1990 |
| 138.114.0.0/16 | 65.5k | ARIN | US | 4th May 1990 |
| 138.128.128.0/23 | 512 | ARIN | US | 17th May 1990 |
| 138.129.16.0/20 | 4.1k | ARIN | US | 17th May 1990 |
| 138.129.32.0/19 | 8.2k | ARIN | US | 17th May 1990 |
| 138.129.64.0/18 | 16.4k | ARIN | US | 17th May 1990 |
| 138.193.0.0/16 | 65.5k | ARIN | US | 21st May 1990 |