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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
26,941 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 204.130.242.0/24 | 256 | ARIN |  US | 15th Dec 1994 |
| 204.130.243.0/24 | 256 | ARIN | US | 16th Dec 1994 |
| 204.130.245.0/24 | 256 | ARIN | US | 19th Dec 1994 |
| 204.130.246.0/24 | 256 | ARIN | US | 19th Dec 1994 |
| 204.130.247.0/24 | 256 | ARIN | US | 19th Dec 1994 |
| 204.130.248.0/24 | 256 | ARIN | US | 20th Dec 1994 |
| 204.130.250.0/24 | 256 | ARIN | US | 20th Dec 1994 |
| 204.130.251.0/24 | 256 | ARIN | US | 20th Dec 1994 |
| 204.130.252.0/24 | 256 | ARIN | US | 20th Dec 1994 |
| 204.130.254.0/24 | 256 | ARIN | US | 20th Dec 1994 |
| 204.130.32.0/19 | 8.2k | ARIN | US | 20th Dec 1994 |
| 204.137.12.0/24 | 256 | ARIN | US | 3rd Apr 2024 |
| 204.137.8.0/22 | 1k | ARIN | US | 12th Feb 2026 |
| 204.138.100.0/23 | 512 | ARIN | US | 5th Jan 2011 |
| 204.138.112.0/24 | 256 | ARIN | US | 10th Jan 2011 |
| 204.138.150.0/24 | 256 | ARIN | US | 5th Oct 2026 |
| 204.138.188.0/24 | 256 | ARIN | US | 30th Aug 1994 |
| 204.138.190.0/24 | 256 | ARIN | US | 16th Feb 2021 |
| 204.138.76.0/22 | 1k | ARIN | US | 1st Oct 2026 |
| 204.138.95.0/24 | 256 | ARIN | US | 6th Oct 2026 |
| 204.138.97.0/24 | 256 | ARIN | US | 30th Aug 1994 |
| 204.138.98.0/24 | 256 | ARIN | US | 30th Aug 1994 |
| 204.139.128.0/17 | 32.8k | ARIN | US | 28th Nov 1994 |
| 204.139.16.0/20 | 4.1k | ARIN | US | 1st Sept 1994 |
| 204.14.168.0/21 | 2k | ARIN | US | 6th Jul 2005 |
| 204.14.204.0/22 | 1k | ARIN | US | 3rd Oct 2024 |
| 204.14.216.0/21 | 2k | ARIN | US | 21st Jul 2005 |
| 204.140.0.0/20 | 4.1k | ARIN | US | 12th Sept 1994 |
| 204.144.100.0/24 | 256 | ARIN | US | 4th Jan 1995 |
| 204.144.101.0/24 | 256 | ARIN | US | 4th Jan 1995 |
| 204.144.102.0/24 | 256 | ARIN | US | 4th Jan 1995 |
| 204.144.103.0/24 | 256 | ARIN | US | 4th Jan 1995 |
| 204.144.105.0/24 | 256 | ARIN | US | 4th Jan 1995 |
| 204.144.107.0/24 | 256 | ARIN | US | 4th Jan 1995 |
| 204.144.108.0/24 | 256 | ARIN | US | 4th Jan 1995 |
| 204.144.109.0/24 | 256 | ARIN | US | 5th Jan 1995 |
| 204.144.110.0/24 | 256 | ARIN | US | 5th Jan 1995 |
| 204.144.111.0/24 | 256 | ARIN | US | 5th Jan 1995 |
| 204.144.112.0/24 | 256 | ARIN | US | 5th Jan 1995 |
| 204.144.115.0/24 | 256 | ARIN | US | 5th Jan 1995 |
| 204.144.116.0/24 | 256 | ARIN | US | 5th Jan 1995 |
| 204.144.117.0/24 | 256 | ARIN | US | 5th Jan 1995 |
| 204.144.118.0/23 | 512 | ARIN | US | 18th Jan 2011 |
| 204.144.150.0/24 | 256 | ARIN | US | 2nd Oct 2026 |
| 204.144.56.0/24 | 256 | ARIN | US | 12th Sept 1994 |
| 204.144.64.0/24 | 256 | ARIN | US | 4th Jan 1995 |
| 204.144.65.0/24 | 256 | ARIN | US | 4th Jan 1995 |
| 204.144.66.0/24 | 256 | ARIN | US | 4th Jan 1995 |
| 204.144.67.0/24 | 256 | ARIN | US | 4th Jan 1995 |
| 204.144.68.0/24 | 256 | ARIN | US | 4th Jan 1995 |