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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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 in United States
26,277 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 15.203.0.0/16 | 65.5k | ARIN |  US | 11th Jul 2022 |
| 15.225.0.0/16 | 65.5k | ARIN | US | 9th Nov 2023 |
| 15.226.0.0/16 | 65.5k | ARIN | US | 9th Nov 2023 |
| 15.243.0.0/16 | 65.5k | ARIN | US | 9th Nov 2023 |
| 15.96.0.0/14 | 262k | ARIN | US | 1st Jul 1994 |
| 150.102.0.0/16 | 65.5k | ARIN | US | 25th Jan 2024 |
| 150.103.0.0/16 | 65.5k | ARIN | US | 25th Jan 2024 |
| 150.110.0.0/16 | 65.5k | ARIN | US | 4th Jun 1991 |
| 150.123.0.0/16 | 65.5k | ARIN | US | 12th Sept 1991 |
| 150.124.0.0/16 | 65.5k | ARIN | US | 12th Sept 1991 |
| 150.127.0.0/16 | 65.5k | ARIN | US | 12th Sept 1991 |
| 150.141.0.0/16 | 65.5k | ARIN | US | 16th May 1991 |
| 150.159.0.0/16 | 65.5k | ARIN | US | 20th May 1991 |
| 150.166.0.0/16 | 65.5k | ARIN | US | 20th May 1991 |
| 150.170.0.0/16 | 65.5k | ARIN | US | 22nd May 1991 |
| 150.172.0.0/16 | 65.5k | ARIN | US | 22nd May 1991 |
| 150.190.0.0/16 | 65.5k | ARIN | US | 30th May 1991 |
| 150.195.240.0/20 | 4.1k | ARIN | US | 25th Jan 2021 |
| 150.215.0.0/16 | 65.5k | ARIN | US | 11th Jun 1991 |
| 150.222.0.0/16 | 65.5k | ARIN | US | 27th Dec 2017 |
| 150.225.0.0/16 | 65.5k | ARIN | US | 5th Aug 1991 |
| 150.233.0.0/16 | 65.5k | ARIN | US | 9th Aug 1991 |
| 150.234.0.0/16 | 65.5k | ARIN | US | 9th Aug 1991 |
| 150.235.0.0/16 | 65.5k | ARIN | US | 9th Aug 1991 |
| 150.247.128.0/17 | 32.8k | ARIN | US | 5th Aug 1991 |
| 150.247.48.0/20 | 4.1k | ARIN | US | 5th Aug 1991 |
| 150.247.96.0/19 | 8.2k | ARIN | US | 5th Aug 1991 |
| 150.252.112.0/20 | 4.1k | ARIN | US | 19th Aug 1991 |
| 150.40.72.0/21 | 2k | ARIN | US | 26th Jun 2024 |
| 150.40.80.0/20 | 4.1k | ARIN | US | 26th Jun 2024 |
| 151.108.0.0/16 | 65.5k | ARIN | US | 30th May 1991 |
| 151.109.0.0/16 | 65.5k | ARIN | US | 16th May 1991 |
| 151.116.0.0/15 | 131k | ARIN | US | 11th Jun 1991 |
| 151.118.0.0/16 | 65.5k | ARIN | US | 11th Jun 1991 |
| 151.119.0.0/16 | 65.5k | ARIN | US | 11th Jun 1991 |
| 151.126.0.0/16 | 65.5k | ARIN | US | 17th Jun 1991 |
| 151.128.0.0/16 | 65.5k | ARIN | US | 17th Jun 1991 |
| 151.148.16.0/20 | 4.1k | ARIN | US | 19th Sept 2022 |
| 151.148.8.0/21 | 2k | ARIN | US | 19th Sept 2022 |
| 151.167.0.0/16 | 65.5k | ARIN | US | 7th Aug 1991 |
| 151.168.0.0/16 | 65.5k | ARIN | US | 7th Aug 1991 |
| 151.171.0.0/16 | 65.5k | ARIN | US | 5th Sept 1991 |
| 151.174.0.0/16 | 65.5k | ARIN | US | 5th Sept 1991 |
| 151.181.128.0/19 | 8.2k | ARIN | US | 17th Sept 1991 |
| 151.181.176.0/20 | 4.1k | ARIN | US | 17th Sept 1991 |
| 151.185.128.0/18 | 16.4k | ARIN | US | 8th Jul 2026 |
| 151.209.0.0/16 | 65.5k | ARIN | US | 25th Sept 1991 |
| 151.210.64.0/19 | 8.2k | ARIN | US | 31st Jul 2026 |
| 152.100.0.0/16 | 65.5k | ARIN | US | 12th Sept 1991 |
| 152.116.0.0/16 | 65.5k | ARIN | US | 13th Aug 1991 |