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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
26,302 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 204.17.229.0/24 | 256 | ARIN |  US | 17th Jun 1994 |
| 204.17.230.0/23 | 512 | ARIN | US | 17th Jun 1994 |
| 204.17.234.0/24 | 256 | ARIN | US | 17th Jun 1994 |
| 204.17.235.0/24 | 256 | ARIN | US | 17th Jun 1994 |
| 204.17.236.0/24 | 256 | ARIN | US | 17th Jun 1994 |
| 204.17.238.0/23 | 512 | ARIN | US | 17th Jun 1994 |
| 204.17.240.0/24 | 256 | ARIN | US | 17th Jun 1994 |
| 204.17.241.0/24 | 256 | ARIN | US | 30th Jul 2026 |
| 204.17.243.0/24 | 256 | ARIN | US | 17th Jun 1994 |
| 204.17.248.0/24 | 256 | ARIN | US | 17th Jun 1994 |
| 204.17.252.0/23 | 512 | ARIN | US | 20th Jun 1994 |
| 204.17.254.0/24 | 256 | ARIN | US | 20th Jun 1994 |
| 204.17.255.0/24 | 256 | ARIN | US | 10th May 2011 |
| 204.172.0.0/15 | 131k | ARIN | US | 6th Oct 1994 |
| 204.174.0.0/24 | 256 | ARIN | US | 4th Jan 2011 |
| 204.174.225.0/24 | 256 | ARIN | US | 19th Nov 2024 |
| 204.174.255.0/24 | 256 | ARIN | US | 6th Jan 2011 |
| 204.174.37.0/24 | 256 | ARIN | US | 1st Jul 2025 |
| 204.174.47.0/24 | 256 | ARIN | US | 8th Apr 2025 |
| 204.174.51.0/24 | 256 | ARIN | US | 4th Jan 2024 |
| 204.175.0.0/16 | 65.5k | ARIN | US | 26th Oct 1994 |
| 204.187.11.0/24 | 256 | ARIN | US | 3rd Apr 2025 |
| 204.188.136.0/21 | 2k | ARIN | US | 9th Nov 1994 |
| 204.189.0.0/16 | 65.5k | ARIN | US | 9th Nov 1994 |
| 204.19.15.0/24 | 256 | ARIN | US | 9th Jun 2011 |
| 204.19.204.0/23 | 512 | ARIN | US | 23rd Aug 2011 |
| 204.19.242.0/24 | 256 | ARIN | US | 26th May 2011 |
| 204.19.255.0/24 | 256 | ARIN | US | 27th May 2011 |
| 204.194.104.0/22 | 1k | ARIN | US | 7th Jan 1995 |
| 204.194.108.0/23 | 512 | ARIN | US | 7th Jan 1995 |
| 204.194.110.0/24 | 256 | ARIN | US | 7th Jan 1995 |
| 204.194.144.0/20 | 4.1k | ARIN | US | 7th Jan 1995 |
| 204.194.16.0/22 | 1k | ARIN | US | 30th Nov 1994 |
| 204.194.160.0/21 | 2k | ARIN | US | 7th Jan 1995 |
| 204.194.20.0/24 | 256 | ARIN | US | 30th Nov 1994 |
| 204.194.200.0/22 | 1k | ARIN | US | 12th Jan 1995 |
| 204.194.204.0/23 | 512 | ARIN | US | 12th Jan 1995 |
| 204.194.206.0/24 | 256 | ARIN | US | 12th Jan 1995 |
| 204.194.208.0/22 | 1k | ARIN | US | 12th Jan 1995 |
| 204.194.212.0/23 | 512 | ARIN | US | 12th Jan 1995 |
| 204.194.224.0/21 | 2k | ARIN | US | 20th Jan 1995 |
| 204.194.24.0/22 | 1k | ARIN | US | 2nd Dec 1994 |
| 204.194.240.0/21 | 2k | ARIN | US | 2nd Feb 1995 |
| 204.194.32.0/21 | 2k | ARIN | US | 11th Dec 1994 |
| 204.194.6.0/24 | 256 | ARIN | US | 29th Nov 1994 |
| 204.194.64.0/21 | 2k | ARIN | US | 19th Dec 1994 |
| 204.197.208.0/20 | 4.1k | ARIN | US | 5th Oct 2010 |
| 204.209.255.0/24 | 256 | ARIN | US | 16th Jun 2017 |
| 204.209.66.0/23 | 512 | ARIN | US | 22nd Dec 2020 |
| 204.209.9.0/24 | 256 | ARIN | US | 8th Oct 2025 |