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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
27,021 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 204.75.152.0/24 | 256 | ARIN |  US | 14th Jul 2026 |
| 204.75.153.0/24 | 256 | ARIN | US | 1st Sept 1994 |
| 204.75.154.0/24 | 256 | ARIN | US | 2nd Dec 1996 |
| 204.75.156.0/24 | 256 | ARIN | US | 1st Sept 1994 |
| 204.75.158.0/24 | 256 | ARIN | US | 27th Dec 2024 |
| 204.75.159.0/24 | 256 | ARIN | US | 1st Sept 1994 |
| 204.75.16.0/24 | 256 | ARIN | US | 23rd Jun 1994 |
| 204.75.160.0/24 | 256 | ARIN | US | 1st Sept 1994 |
| 204.75.161.0/24 | 256 | ARIN | US | 2nd Sept 1994 |
| 204.75.162.0/24 | 256 | ARIN | US | 2nd Sept 1994 |
| 204.75.163.0/24 | 256 | ARIN | US | 2nd Sept 1994 |
| 204.75.165.0/24 | 256 | ARIN | US | 2nd Sept 1994 |
| 204.75.166.0/24 | 256 | ARIN | US | 2nd Sept 1994 |
| 204.75.167.0/24 | 256 | ARIN | US | 2nd Sept 1994 |
| 204.75.168.0/24 | 256 | ARIN | US | 2nd Sept 1994 |
| 204.75.17.0/24 | 256 | ARIN | US | 9th Mar 2026 |
| 204.75.171.0/24 | 256 | ARIN | US | 2nd Sept 1994 |
| 204.75.174.0/24 | 256 | ARIN | US | 2nd Sept 1994 |
| 204.75.175.0/24 | 256 | ARIN | US | 2nd Sept 1994 |
| 204.75.177.0/24 | 256 | ARIN | US | 2nd Sept 1994 |
| 204.75.179.0/24 | 256 | ARIN | US | 2nd Sept 1994 |
| 204.75.180.0/22 | 1k | ARIN | US | 2nd Sept 1994 |
| 204.75.184.0/24 | 256 | ARIN | US | 2nd Sept 1994 |
| 204.75.186.0/23 | 512 | ARIN | US | 6th Mar 2024 |
| 204.75.188.0/23 | 512 | ARIN | US | 6th Aug 2024 |
| 204.75.193.0/24 | 256 | ARIN | US | 6th Sept 1994 |
| 204.75.194.0/23 | 512 | ARIN | US | 6th Sept 1994 |
| 204.75.196.0/24 | 256 | ARIN | US | 6th Sept 1994 |
| 204.75.20.0/22 | 1k | ARIN | US | 23rd Jun 1994 |
| 204.75.201.0/24 | 256 | ARIN | US | 7th Sept 1994 |
| 204.75.202.0/24 | 256 | ARIN | US | 7th Sept 1994 |
| 204.75.203.0/24 | 256 | ARIN | US | 7th Sept 1994 |
| 204.75.204.0/24 | 256 | ARIN | US | 7th Sept 1994 |
| 204.75.205.0/24 | 256 | ARIN | US | 7th Sept 1994 |
| 204.75.206.0/24 | 256 | ARIN | US | 7th Sept 1994 |
| 204.75.209.0/24 | 256 | ARIN | US | 7th Sept 1994 |
| 204.75.210.0/24 | 256 | ARIN | US | 7th Sept 1994 |
| 204.75.211.0/24 | 256 | ARIN | US | 7th Sept 1994 |
| 204.75.212.0/24 | 256 | ARIN | US | 7th Sept 1994 |
| 204.75.213.0/24 | 256 | ARIN | US | 7th Sept 1994 |
| 204.75.214.0/24 | 256 | ARIN | US | 7th Sept 1994 |
| 204.75.215.0/24 | 256 | ARIN | US | 7th Sept 1994 |
| 204.75.216.0/24 | 256 | ARIN | US | 7th Sept 1994 |
| 204.75.217.0/24 | 256 | ARIN | US | 7th Sept 1994 |
| 204.75.218.0/24 | 256 | ARIN | US | 8th Sept 1994 |
| 204.75.219.0/24 | 256 | ARIN | US | 8th Sept 1994 |
| 204.75.220.0/24 | 256 | ARIN | US | 8th Sept 1994 |
| 204.75.221.0/24 | 256 | ARIN | US | 8th Sept 1994 |
| 204.75.222.0/24 | 256 | ARIN | US | 8th Sept 1994 |
| 204.75.223.0/24 | 256 | ARIN | US | 8th Sept 1994 |