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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
30,430 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 143.131.64.0/18 | 16.4k | ARIN |  US | 19th Sept 1990 |
| 143.162.0.0/16 | 65.5k | ARIN | US | 26th Sept 1990 |
| 143.173.0.0/16 | 65.5k | ARIN | US | 30th Jun 1990 |
| 143.181.0.0/16 | 65.5k | ARIN | US | 1st Oct 1990 |
| 143.182.0.0/16 | 65.5k | ARIN | US | 1st Oct 1990 |
| 143.183.0.0/16 | 65.5k | ARIN | US | 1st Oct 1990 |
| 143.184.0.0/16 | 65.5k | ARIN | US | 1st Oct 1990 |
| 143.185.0.0/16 | 65.5k | ARIN | US | 1st Oct 1990 |
| 143.190.0.0/16 | 65.5k | ARIN | US | 1st Oct 1990 |
| 143.192.64.0/19 | 8.2k | ARIN | US | 1st Oct 1990 |
| 143.193.0.0/16 | 65.5k | ARIN | US | 30th Jun 1990 |
| 143.219.0.0/16 | 65.5k | ARIN | US | 30th Jun 1990 |
| 143.222.0.0/16 | 65.5k | ARIN | US | 30th Jun 1990 |
| 143.223.136.0/24 | 256 | ARIN | US | 30th Jun 1990 |
| 143.223.140.0/23 | 512 | ARIN | US | 30th Jun 1990 |
| 143.223.16.0/23 | 512 | ARIN | US | 18th Feb 2026 |
| 143.223.160.0/24 | 256 | ARIN | US | 20th Feb 2026 |
| 143.223.161.0/24 | 256 | ARIN | US | 30th Jun 1990 |
| 143.223.164.0/22 | 1k | ARIN | US | 30th Jun 1990 |
| 143.223.173.0/24 | 256 | ARIN | US | 30th Jun 1990 |
| 143.223.175.0/24 | 256 | ARIN | US | 30th Jun 1990 |
| 143.223.180.0/22 | 1k | ARIN | US | 30th Jun 1990 |
| 143.223.20.0/22 | 1k | ARIN | US | 30th Jun 1990 |
| 143.242.0.0/16 | 65.5k | ARIN | US | 23rd Oct 1990 |
| 143.243.0.0/16 | 65.5k | ARIN | US | 23rd Oct 1990 |
| 143.246.128.0/21 | 2k | ARIN | US | 1st Apr 2025 |
| 143.246.176.0/22 | 1k | ARIN | US | 26th Oct 1990 |
| 143.246.184.0/21 | 2k | ARIN | US | 24th Jul 2026 |
| 143.246.224.0/20 | 4.1k | ARIN | US | 21st Jul 2026 |
| 143.246.240.0/21 | 2k | ARIN | US | 26th Oct 1990 |
| 143.246.64.0/18 | 16.4k | ARIN | US | 26th Oct 1990 |
| 143.247.0.0/16 | 65.5k | ARIN | US | 26th Oct 1990 |
| 143.251.0.0/16 | 65.5k | ARIN | US | 26th Oct 1990 |
| 143.41.0.0/16 | 65.5k | ARIN | US | 24th Jul 2023 |
| 143.49.0.0/16 | 65.5k | ARIN | US | 26th Mar 1990 |
| 143.55.154.0/24 | 256 | ARIN | US | 15th May 2020 |
| 143.63.0.0/16 | 65.5k | ARIN | US | 26th Mar 1990 |
| 143.82.0.0/16 | 65.5k | ARIN | US | 26th Mar 1990 |
| 143.91.0.0/16 | 65.5k | ARIN | US | 7th Sept 1990 |
| 143.98.0.0/16 | 65.5k | ARIN | US | 7th Sept 1990 |
| 144.10.0.0/16 | 65.5k | ARIN | US | 28th Jan 2021 |
| 144.111.0.0/16 | 65.5k | ARIN | US | 3rd Dec 1990 |
| 144.112.0.0/16 | 65.5k | ARIN | US | 3rd Dec 1990 |
| 144.113.0.0/16 | 65.5k | ARIN | US | 3rd Dec 1990 |
| 144.114.0.0/16 | 65.5k | ARIN | US | 3rd Dec 1990 |
| 144.115.0.0/16 | 65.5k | ARIN | US | 3rd Dec 1990 |
| 144.116.0.0/16 | 65.5k | ARIN | US | 3rd Dec 1990 |
| 144.117.0.0/16 | 65.5k | ARIN | US | 3rd Dec 1990 |
| 144.14.0.0/16 | 65.5k | ARIN | US | 6th Nov 1990 |
| 144.148.0.0/16 | 65.5k | ARIN | US | 13th Dec 1990 |