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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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 |
|---|---|---|---|---|
| 204.52.207.0/24 | 256 | ARIN |  US | 11th Jul 1994 |
| 204.52.210.0/24 | 256 | ARIN | US | 11th Jul 1994 |
| 204.52.211.0/24 | 256 | ARIN | US | 11th Jul 1994 |
| 204.52.217.0/24 | 256 | ARIN | US | 12th Jul 1994 |
| 204.52.220.0/24 | 256 | ARIN | US | 12th Jul 1994 |
| 204.52.226.0/24 | 256 | ARIN | US | 12th Jul 1994 |
| 204.52.228.0/23 | 512 | ARIN | US | 13th Jul 1994 |
| 204.52.230.0/24 | 256 | ARIN | US | 13th Jul 1994 |
| 204.52.232.0/24 | 256 | ARIN | US | 3rd Aug 2011 |
| 204.52.233.0/24 | 256 | ARIN | US | 13th Jul 1994 |
| 204.52.236.0/24 | 256 | ARIN | US | 14th Jul 1994 |
| 204.52.239.0/24 | 256 | ARIN | US | 14th Jul 1994 |
| 204.52.240.0/24 | 256 | ARIN | US | 14th Jul 1994 |
| 204.52.241.0/24 | 256 | ARIN | US | 14th Jul 1994 |
| 204.52.250.0/24 | 256 | ARIN | US | 15th Jul 1994 |
| 204.52.251.0/24 | 256 | ARIN | US | 15th Jul 1994 |
| 204.52.253.0/24 | 256 | ARIN | US | 15th Jul 1994 |
| 204.52.255.0/24 | 256 | ARIN | US | 15th Jul 1994 |
| 204.56.8.0/21 | 2k | ARIN | US | 31st May 1994 |
| 204.56.96.0/19 | 8.2k | ARIN | US | 12th Sept 1994 |
| 204.57.0.0/21 | 2k | ARIN | US | 31st May 1994 |
| 204.57.192.0/20 | 4.1k | ARIN | US | 18th Jul 1994 |
| 204.57.219.0/24 | 256 | ARIN | US | 20th Jan 2026 |
| 204.58.10.0/24 | 256 | ARIN | US | 13th Jun 1994 |
| 204.58.128.0/23 | 512 | ARIN | US | 15th Jan 1995 |
| 204.58.130.0/24 | 256 | ARIN | US | 15th Jan 1995 |
| 204.58.131.0/24 | 256 | ARIN | US | 16th Aug 2011 |
| 204.58.132.0/23 | 512 | ARIN | US | 15th Jan 1995 |
| 204.58.134.0/24 | 256 | ARIN | US | 15th Jan 1995 |
| 204.58.140.0/22 | 1k | ARIN | US | 16th Jan 1995 |
| 204.58.147.0/24 | 256 | ARIN | US | 17th Aug 2011 |
| 204.58.148.0/22 | 1k | ARIN | US | 24th Jan 1995 |
| 204.58.16.0/21 | 2k | ARIN | US | 14th Jun 1994 |
| 204.58.172.0/22 | 1k | ARIN | US | 30th Jan 1995 |
| 204.58.184.0/22 | 1k | ARIN | US | 8th Feb 1995 |
| 204.58.188.0/22 | 1k | ARIN | US | 8th Feb 1995 |
| 204.58.192.0/22 | 1k | ARIN | US | 8th Feb 1995 |
| 204.58.200.0/22 | 1k | ARIN | US | 16th Feb 1995 |
| 204.58.208.0/22 | 1k | ARIN | US | 16th Feb 1995 |
| 204.58.212.0/22 | 1k | ARIN | US | 16th Feb 1995 |
| 204.58.220.0/22 | 1k | ARIN | US | 17th Feb 1995 |
| 204.58.228.0/22 | 1k | ARIN | US | 19th Dec 2008 |
| 204.58.236.0/22 | 1k | ARIN | US | 8th Mar 1995 |
| 204.58.24.0/22 | 1k | ARIN | US | 28th Feb 1995 |
| 204.58.245.0/24 | 256 | ARIN | US | 9th Mar 1995 |
| 204.58.248.0/24 | 256 | ARIN | US | 9th Mar 1995 |
| 204.58.250.0/23 | 512 | ARIN | US | 20th Mar 1995 |
| 204.58.252.0/23 | 512 | ARIN | US | 20th Mar 1995 |
| 204.58.28.0/22 | 1k | ARIN | US | 2nd Mar 1995 |
| 204.58.8.0/23 | 512 | ARIN | US | 13th Jun 1994 |