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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
26,936 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 203.27.64.0/24 | 256 | ARIN |  US | 9th Aug 2021 |
| 203.28.248.0/24 | 256 | ARIN | US | 5th Jan 2021 |
| 203.31.244.0/23 | 512 | ARIN | US | 18th Nov 2024 |
| 203.32.0.0/22 | 1k | APNIC | US | 26th Sept 1996 |
| 203.34.210.0/24 | 256 | APNIC | US | 21st Nov 1996 |
| 203.5.14.0/23 | 512 | APNIC | US | 6th May 1994 |
| 203.6.130.0/24 | 256 | APNIC | US | 11th Jul 1994 |
| 203.62.143.0/24 | 256 | ARIN | US | 23rd Feb 2026 |
| 203.96.184.0/22 | 1k | ARIN | US | 12th Jan 2022 |
| 204.10.0.0/22 | 1k | ARIN | US | 1st Mar 2023 |
| 204.10.189.0/24 | 256 | ARIN | US | 26th Apr 2019 |
| 204.10.40.0/22 | 1k | ARIN | US | 29th Dec 2004 |
| 204.10.96.0/21 | 2k | ARIN | US | 10th Dec 2004 |
| 204.106.18.0/23 | 512 | ARIN | US | 21st Jul 1994 |
| 204.106.20.0/22 | 1k | ARIN | US | 21st Jul 1994 |
| 204.106.24.0/21 | 2k | ARIN | US | 21st Jul 1994 |
| 204.106.64.0/18 | 16.4k | ARIN | US | 6th Feb 1995 |
| 204.107.0.0/21 | 2k | ARIN | US | 25th Jul 1994 |
| 204.107.100.0/24 | 256 | ARIN | US | 11th Oct 1994 |
| 204.107.101.0/24 | 256 | ARIN | US | 11th Oct 1994 |
| 204.107.103.0/24 | 256 | ARIN | US | 12th Oct 1994 |
| 204.107.104.0/24 | 256 | ARIN | US | 12th Oct 1994 |
| 204.107.105.0/24 | 256 | ARIN | US | 12th Oct 1994 |
| 204.107.106.0/24 | 256 | ARIN | US | 12th Oct 1994 |
| 204.107.107.0/24 | 256 | ARIN | US | 12th Oct 1994 |
| 204.107.108.0/24 | 256 | ARIN | US | 12th Oct 1994 |
| 204.107.109.0/24 | 256 | ARIN | US | 12th Oct 1994 |
| 204.107.110.0/24 | 256 | ARIN | US | 12th Oct 1994 |
| 204.107.112.0/24 | 256 | ARIN | US | 12th Oct 1994 |
| 204.107.113.0/24 | 256 | ARIN | US | 12th Oct 1994 |
| 204.107.114.0/24 | 256 | ARIN | US | 12th Oct 1994 |
| 204.107.116.0/24 | 256 | ARIN | US | 26th Aug 1994 |
| 204.107.117.0/24 | 256 | ARIN | US | 30th Aug 1994 |
| 204.107.119.0/24 | 256 | ARIN | US | 30th Aug 1994 |
| 204.107.120.0/24 | 256 | ARIN | US | 30th Aug 1994 |
| 204.107.121.0/24 | 256 | ARIN | US | 30th Aug 1994 |
| 204.107.122.0/24 | 256 | ARIN | US | 23rd Jun 2011 |
| 204.107.123.0/24 | 256 | ARIN | US | 12th Oct 1994 |
| 204.107.124.0/24 | 256 | ARIN | US | 12th Oct 1994 |
| 204.107.125.0/24 | 256 | ARIN | US | 12th Oct 1994 |
| 204.107.126.0/24 | 256 | ARIN | US | 12th Oct 1994 |
| 204.107.127.0/24 | 256 | ARIN | US | 12th Oct 1994 |
| 204.107.128.0/24 | 256 | ARIN | US | 12th Oct 1994 |
| 204.107.129.0/24 | 256 | ARIN | US | 17th Oct 1994 |
| 204.107.131.0/24 | 256 | ARIN | US | 17th Oct 1994 |
| 204.107.132.0/24 | 256 | ARIN | US | 19th Oct 1994 |
| 204.107.133.0/24 | 256 | ARIN | US | 19th Oct 1994 |
| 204.107.137.0/24 | 256 | ARIN | US | 19th Oct 1994 |
| 204.107.138.0/24 | 256 | ARIN | US | 19th Oct 1994 |
| 204.107.140.0/24 | 256 | ARIN | US | 19th Oct 1994 |