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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
85,458 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 204.17.226.0/24 | 256 | ARIN |  US | 17th Jun 1994 |
| 204.17.228.0/24 | 256 | ARIN | US | 17th Jun 1994 |
| 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 |
| 204.174.1.0/24 | 256 | ARIN |  CA | 17th Oct 1994 |
| 204.174.10.0/23 | 512 | ARIN | CA | 17th Oct 1994 |
| 204.174.101.0/24 | 256 | ARIN | CA | 17th Oct 1994 |
| 204.174.102.0/24 | 256 | ARIN | CA | 17th Oct 1994 |
| 204.174.114.0/24 | 256 | ARIN | CA | 17th Oct 1994 |
| 204.174.118.0/24 | 256 | ARIN | CA | 17th Oct 1994 |
| 204.174.119.0/24 | 256 | ARIN | CA | 17th Oct 1994 |
| 204.174.120.0/22 | 1k | ARIN | CA | 17th Oct 1994 |
| 204.174.124.0/22 | 1k | ARIN | CA | 17th Oct 1994 |
| 204.174.15.0/24 | 256 | ARIN | CA | 17th Oct 1994 |
| 204.174.192.0/21 | 2k | ARIN | CA | 17th Oct 1994 |
| 204.174.2.0/23 | 512 | ARIN | CA | 17th Oct 1994 |
| 204.174.200.0/23 | 512 | ARIN | CA | 17th Oct 1994 |
| 204.174.202.0/24 | 256 | ARIN | CA | 17th Oct 1994 |
| 204.174.203.0/24 | 256 | ARIN | CA | 17th Oct 1994 |
| 204.174.206.0/23 | 512 | ARIN | CA | 17th Oct 1994 |
| 204.174.208.0/23 | 512 | ARIN | CA | 17th Oct 1994 |
| 204.174.210.0/24 | 256 | ARIN | CA | 17th Oct 1994 |
| 204.174.211.0/24 | 256 | ARIN | CA | 17th Oct 1994 |
| 204.174.220.0/23 | 512 | ARIN | CA | 17th Oct 1994 |
| 204.174.225.0/24 | 256 | ARIN | US | 19th Nov 2024 |
| 204.174.228.0/23 | 512 | ARIN | CA | 17th Oct 1994 |
| 204.174.231.0/24 | 256 | ARIN | CA | 17th Oct 1994 |
| 204.174.234.0/24 | 256 | ARIN | CA | 17th Oct 1994 |
| 204.174.235.0/24 | 256 | ARIN | CA | 17th Oct 1994 |
| 204.174.238.0/24 | 256 | ARIN | CA | 17th Oct 1994 |
| 204.174.239.0/24 | 256 | ARIN | CA | 17th Oct 1994 |
| 204.174.255.0/24 | 256 | ARIN | US | 6th Jan 2011 |
| 204.174.32.0/23 | 512 | ARIN | CA | 17th Oct 1994 |
| 204.174.34.0/24 | 256 | ARIN | CA | 17th Oct 1994 |
| 204.174.37.0/24 | 256 | ARIN | US | 1st Jul 2025 |
| 204.174.38.0/24 | 256 | ARIN | CA | 17th Oct 1994 |
| 204.174.39.0/24 | 256 | ARIN | CA | 17th Oct 1994 |