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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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.
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Countries with unannounced space registered through ARIN, largest first.
Unannounced blocks registered through ARIN
30,476 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 204.154.96.0/22 | 1k | ARIN |  US | 17th Oct 1994 |
| 204.155.80.0/21 | 2k | ARIN | US | 5th Oct 1994 |
| 204.155.88.0/22 | 1k | ARIN | US | 5th Oct 1994 |
| 204.155.92.0/23 | 512 | ARIN | US | 5th Oct 1994 |
| 204.155.94.0/24 | 256 | ARIN | US | 5th Oct 1994 |
| 204.156.124.0/22 | 1k | ARIN |  CA | 12th Feb 2009 |
| 204.156.178.0/24 | 256 | ARIN | US | 10th Dec 2014 |
| 204.156.32.0/19 | 8.2k | ARIN | US | 28th Sept 1994 |
| 204.16.104.0/22 | 1k | ARIN | US | 27th Oct 2005 |
| 204.16.116.0/22 | 1k | ARIN | US | 22nd Aug 2012 |
| 204.16.152.0/21 | 2k | ARIN | US | 3rd Nov 2005 |
| 204.16.16.0/22 | 1k | ARIN | US | 22nd Nov 2005 |
| 204.16.208.0/22 | 1k | ARIN | US | 20th Mar 2009 |
| 204.16.72.0/22 | 1k | ARIN | US | 30th Sept 2025 |
| 204.17.0.0/21 | 2k | ARIN | US | 9th May 1994 |
| 204.17.128.0/23 | 512 | ARIN | US | 8th Jun 1994 |
| 204.17.138.0/24 | 256 | ARIN | US | 8th Jun 1994 |
| 204.17.141.0/24 | 256 | ARIN | US | 9th Jun 1994 |
| 204.17.145.0/24 | 256 | ARIN | US | 9th Jun 1994 |
| 204.17.148.0/24 | 256 | ARIN | US | 9th Jun 1994 |
| 204.17.149.0/24 | 256 | ARIN | US | 9th Jun 1994 |
| 204.17.151.0/24 | 256 | ARIN | US | 9th Jun 1994 |
| 204.17.152.0/24 | 256 | ARIN | US | 10th Jun 1994 |
| 204.17.153.0/24 | 256 | ARIN | US | 13th Jun 1994 |
| 204.17.154.0/24 | 256 | ARIN | CA | 7th Jan 2011 |
| 204.17.155.0/24 | 256 | ARIN | US | 13th Jun 1994 |
| 204.17.156.0/24 | 256 | ARIN | US | 13th Jun 1994 |
| 204.17.164.0/24 | 256 | ARIN | US | 13th Jun 1994 |
| 204.17.165.0/24 | 256 | ARIN | US | 13th Jun 1994 |
| 204.17.166.0/24 | 256 | ARIN | US | 13th Jun 1994 |
| 204.17.167.0/24 | 256 | ARIN | US | 13th Jun 1994 |
| 204.17.168.0/24 | 256 | ARIN | US | 14th Jun 1994 |
| 204.17.170.0/23 | 512 | ARIN | US | 14th Jun 1994 |
| 204.17.172.0/22 | 1k | ARIN | US | 14th Jun 1994 |
| 204.17.180.0/24 | 256 | ARIN | US | 14th Jun 1994 |
| 204.17.181.0/24 | 256 | ARIN | US | 14th Jun 1994 |
| 204.17.182.0/24 | 256 | ARIN | US | 15th Jun 1994 |
| 204.17.183.0/24 | 256 | ARIN | US | 15th Jun 1994 |
| 204.17.184.0/24 | 256 | ARIN | US | 15th Jun 1994 |
| 204.17.185.0/24 | 256 | ARIN | US | 15th Jun 1994 |
| 204.17.186.0/24 | 256 | ARIN | US | 15th Jun 1994 |
| 204.17.188.0/24 | 256 | ARIN | US | 15th Jun 1994 |
| 204.17.189.0/24 | 256 | ARIN | US | 15th Jun 1994 |
| 204.17.190.0/23 | 512 | ARIN | US | 15th Jun 1994 |
| 204.17.192.0/24 | 256 | ARIN | US | 15th Jun 1994 |
| 204.17.193.0/24 | 256 | ARIN | US | 15th Jun 1994 |
| 204.17.194.0/24 | 256 | ARIN | US | 15th Jun 1994 |
| 204.17.198.0/23 | 512 | ARIN | US | 15th Jun 1994 |
| 204.17.200.0/24 | 256 | ARIN | US | 15th Jun 1994 |
| 204.17.201.0/24 | 256 | ARIN | US | 15th Jun 1994 |