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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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 |
|---|---|---|---|---|
| 204.27.254.0/24 | 256 | ARIN |  US | 9th Dec 1994 |
| 204.27.255.0/24 | 256 | ARIN | US | 9th Dec 1994 |
| 204.27.32.0/20 | 4.1k | ARIN | US | 18th May 1994 |
| 204.27.48.0/22 | 1k | ARIN | US | 18th May 1994 |
| 204.28.10.0/23 | 512 | ARIN | US | 24th Aug 2011 |
| 204.28.128.0/18 | 16.4k | ARIN | US | 8th Jun 1994 |
| 204.28.192.0/20 | 4.1k | ARIN | US | 8th Jun 1994 |
| 204.28.208.0/21 | 2k | ARIN | US | 10th Jul 2026 |
| 204.28.216.0/22 | 1k | ARIN | US | 21st Jul 2026 |
| 204.28.220.0/23 | 512 | ARIN | US | 8th Jun 1994 |
| 204.28.222.0/24 | 256 | ARIN | US | 17th Jul 2026 |
| 204.28.32.0/19 | 8.2k | ARIN | US | 24th Jun 1994 |
| 204.28.8.0/23 | 512 | ARIN | US | 18th May 1994 |
| 204.29.0.0/21 | 2k | ARIN | US | 29th Jun 1994 |
| 204.29.10.0/24 | 256 | ARIN | US | 29th Jun 1994 |
| 204.29.128.0/24 | 256 | ARIN | US | 20th Jun 1994 |
| 204.29.129.0/24 | 256 | ARIN | US | 20th Jun 1994 |
| 204.29.130.0/24 | 256 | ARIN | US | 20th Jun 1994 |
| 204.29.135.0/24 | 256 | ARIN | US | 21st Jun 1994 |
| 204.29.136.0/24 | 256 | ARIN | US | 21st Jun 1994 |
| 204.29.137.0/24 | 256 | ARIN | US | 21st Jun 1994 |
| 204.29.138.0/24 | 256 | ARIN | US | 21st Jun 1994 |
| 204.29.140.0/24 | 256 | ARIN | US | 21st Jun 1994 |
| 204.29.141.0/24 | 256 | ARIN | US | 21st Jun 1994 |
| 204.29.142.0/24 | 256 | ARIN | US | 25th Mar 2025 |
| 204.29.143.0/24 | 256 | ARIN | US | 21st Jun 1994 |
| 204.29.144.0/24 | 256 | ARIN | US | 21st Jun 1994 |
| 204.29.145.0/24 | 256 | ARIN | US | 21st Jun 1994 |
| 204.29.147.0/24 | 256 | ARIN | US | 22nd Jun 1994 |
| 204.29.148.0/24 | 256 | ARIN | US | 22nd Jun 1994 |
| 204.29.149.0/24 | 256 | ARIN | US | 22nd Jun 1994 |
| 204.29.150.0/23 | 512 | ARIN | US | 22nd Jun 1994 |
| 204.29.152.0/23 | 512 | ARIN | US | 22nd Jun 1994 |
| 204.29.155.0/24 | 256 | ARIN | US | 22nd Jun 1994 |
| 204.29.156.0/23 | 512 | ARIN | US | 22nd Jun 1994 |
| 204.29.158.0/24 | 256 | ARIN | US | 22nd Jun 1994 |
| 204.29.159.0/24 | 256 | ARIN | US | 22nd Jun 1994 |
| 204.29.161.0/24 | 256 | ARIN |  CA | 22nd Jun 1994 |
| 204.29.164.0/24 | 256 | ARIN | US | 22nd Jun 1994 |
| 204.29.165.0/24 | 256 | ARIN | US | 22nd Jun 1994 |
| 204.29.169.0/24 | 256 | ARIN | US | 23rd Jun 1994 |
| 204.29.170.0/24 | 256 | ARIN | US | 23rd Jun 1994 |
| 204.29.176.0/22 | 1k | ARIN | US | 23rd Jun 1994 |
| 204.29.180.0/24 | 256 | ARIN | US | 23rd Jun 1994 |
| 204.29.181.0/24 | 256 | ARIN | US | 23rd Jun 1994 |
| 204.29.182.0/24 | 256 | ARIN | US | 23rd Jun 1994 |
| 204.29.183.0/24 | 256 | ARIN | US | 23rd Jun 1994 |
| 204.29.184.0/24 | 256 | ARIN | US | 23rd Jun 1994 |
| 204.29.186.0/23 | 512 | ARIN | US | 5th Dec 1996 |
| 204.29.188.0/24 | 256 | ARIN | US | 23rd Jun 1994 |