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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
Browse by country
Countries with the most unannounced blocks, largest first.
Unannounced blocks
85,458 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 204.174.43.0/24 | 256 | ARIN |  CA | 17th Oct 1994 |
| 204.174.44.0/23 | 512 | ARIN | CA | 17th Oct 1994 |
| 204.174.46.0/24 | 256 | ARIN | CA | 17th Oct 1994 |
| 204.174.47.0/24 | 256 | ARIN |  US | 8th Apr 2025 |
| 204.174.48.0/23 | 512 | ARIN | CA | 17th Oct 1994 |
| 204.174.50.0/24 | 256 | ARIN | CA | 7th Nov 1994 |
| 204.174.51.0/24 | 256 | ARIN | US | 4th Jan 2024 |
| 204.174.52.0/23 | 512 | ARIN | CA | 17th Oct 1994 |
| 204.174.54.0/24 | 256 | ARIN | CA | 17th Oct 1994 |
| 204.174.55.0/24 | 256 | ARIN | CA | 17th Oct 1994 |
| 204.174.6.0/23 | 512 | ARIN | CA | 17th Oct 1994 |
| 204.174.70.0/24 | 256 | ARIN | CA | 17th Oct 1994 |
| 204.174.71.0/24 | 256 | ARIN | CA | 17th Oct 1994 |
| 204.174.72.0/23 | 512 | ARIN | CA | 17th Oct 1994 |
| 204.174.74.0/24 | 256 | ARIN | CA | 17th Oct 1994 |
| 204.174.8.0/24 | 256 | ARIN | CA | 17th Oct 1994 |
| 204.174.9.0/24 | 256 | ARIN | CA | 17th Oct 1994 |
| 204.175.0.0/16 | 65.5k | ARIN | US | 26th Oct 1994 |
| 204.187.1.0/24 | 256 | ARIN | CA | 7th Nov 1994 |
| 204.187.10.0/24 | 256 | ARIN | CA | 7th Nov 1994 |
| 204.187.104.0/24 | 256 | ARIN | CA | 7th Nov 1994 |
| 204.187.106.0/23 | 512 | ARIN | CA | 7th Nov 1994 |
| 204.187.108.0/22 | 1k | ARIN | CA | 7th Nov 1994 |
| 204.187.11.0/24 | 256 | ARIN | US | 3rd Apr 2025 |
| 204.187.112.0/22 | 1k | ARIN | CA | 7th Nov 1994 |
| 204.187.116.0/23 | 512 | ARIN | CA | 7th Nov 1994 |
| 204.187.118.0/23 | 512 | ARIN | CA | 7th Nov 1994 |
| 204.187.120.0/22 | 1k | ARIN | CA | 7th Nov 1994 |
| 204.187.124.0/23 | 512 | ARIN | CA | 7th Nov 1994 |
| 204.187.126.0/24 | 256 | ARIN | CA | 7th Nov 1994 |
| 204.187.127.0/24 | 256 | ARIN | CA | 7th Nov 1994 |
| 204.187.130.0/23 | 512 | ARIN | CA | 7th Nov 1994 |
| 204.187.132.0/24 | 256 | ARIN | CA | 7th Nov 1994 |
| 204.187.133.0/24 | 256 | ARIN | CA | 7th Nov 1994 |
| 204.187.134.0/24 | 256 | ARIN | CA | 7th Nov 1994 |
| 204.187.135.0/24 | 256 | ARIN | CA | 7th Nov 1994 |
| 204.187.139.0/24 | 256 | ARIN | CA | 7th Nov 1994 |
| 204.187.141.0/24 | 256 | ARIN | CA | 7th Nov 1994 |
| 204.187.142.0/23 | 512 | ARIN | CA | 7th Nov 1994 |
| 204.187.145.0/24 | 256 | ARIN | CA | 7th Nov 1994 |
| 204.187.146.0/23 | 512 | ARIN | CA | 7th Nov 1994 |
| 204.187.148.0/22 | 1k | ARIN | CA | 7th Nov 1994 |
| 204.187.154.0/24 | 256 | ARIN | CA | 7th Nov 1994 |
| 204.187.192.0/19 | 8.2k | ARIN | CA | 7th Nov 1994 |
| 204.187.2.0/23 | 512 | ARIN | CA | 7th Nov 1994 |
| 204.187.224.0/20 | 4.1k | ARIN | CA | 7th Nov 1994 |
| 204.187.240.0/21 | 2k | ARIN | CA | 7th Nov 1994 |
| 204.187.248.0/22 | 1k | ARIN | CA | 7th Nov 1994 |
| 204.187.4.0/22 | 1k | ARIN | CA | 7th Nov 1994 |
| 204.187.40.0/21 | 2k | ARIN | CA | 1st Jul 1994 |