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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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 in United States
26,300 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 204.99.151.0/24 | 256 | ARIN |  US | 12th Jul 1994 |
| 204.99.156.0/22 | 1k | ARIN | US | 12th Jul 1994 |
| 204.99.160.0/20 | 4.1k | ARIN | US | 12th Jul 1994 |
| 204.99.176.0/23 | 512 | ARIN | US | 12th Jul 1994 |
| 204.99.180.0/22 | 1k | ARIN | US | 12th Jul 1994 |
| 204.99.186.0/23 | 512 | ARIN | US | 12th Jul 1994 |
| 204.99.188.0/22 | 1k | ARIN | US | 12th Jul 1994 |
| 204.99.224.0/19 | 8.2k | ARIN | US | 12th Jul 1994 |
| 205.132.136.0/21 | 2k | ARIN | US | 30th Apr 1995 |
| 205.132.152.0/21 | 2k | ARIN | US | 4th May 1995 |
| 205.132.184.0/21 | 2k | ARIN | US | 7th Jul 1995 |
| 205.132.200.0/21 | 2k | ARIN | US | 20th Jul 1995 |
| 205.132.208.0/21 | 2k | ARIN | US | 20th Jul 1995 |
| 205.132.224.0/21 | 2k | ARIN | US | 3rd Aug 1995 |
| 205.132.232.0/21 | 2k | ARIN | US | 7th Aug 1995 |
| 205.132.24.0/21 | 2k | ARIN | US | 10th Feb 1995 |
| 205.132.240.0/21 | 2k | ARIN | US | 7th Aug 1995 |
| 205.132.6.0/23 | 512 | ARIN | US | 2nd Feb 1995 |
| 205.132.64.0/21 | 2k | ARIN | US | 3rd Mar 1995 |
| 205.132.88.0/22 | 1k | ARIN | US | 17th Mar 1995 |
| 205.132.92.0/23 | 512 | ARIN | US | 17th Mar 1995 |
| 205.132.96.0/21 | 2k | ARIN | US | 17th Mar 1995 |
| 205.134.232.0/23 | 512 | ARIN | US | 19th Apr 2005 |
| 205.134.235.0/24 | 256 | ARIN | US | 19th Apr 2005 |
| 205.134.236.0/23 | 512 | ARIN | US | 19th Apr 2005 |
| 205.134.240.0/24 | 256 | ARIN | US | 19th Apr 2005 |
| 205.134.242.0/23 | 512 | ARIN | US | 19th Apr 2005 |
| 205.134.248.0/24 | 256 | ARIN | US | 19th Apr 2005 |
| 205.134.64.0/19 | 8.2k | ARIN | US | 9th Mar 1995 |
| 205.134.96.0/19 | 8.2k | ARIN | US | 31st Mar 1995 |
| 205.137.0.0/20 | 4.1k | ARIN | US | 15th Feb 1995 |
| 205.137.128.0/20 | 4.1k | ARIN | US | 10th Mar 1995 |
| 205.137.16.0/20 | 4.1k | ARIN | US | 15th Feb 1995 |
| 205.137.192.0/20 | 4.1k | ARIN | US | 17th Mar 1995 |
| 205.137.224.0/20 | 4.1k | ARIN | US | 30th Apr 1995 |
| 205.137.248.0/24 | 256 | ARIN | US | 29th Sept 2020 |
| 205.140.176.0/20 | 4.1k | ARIN | US | 15th Feb 1995 |
| 205.141.224.0/21 | 2k | ARIN | US | 28th Feb 1995 |
| 205.141.64.0/18 | 16.4k | ARIN | US | 17th Feb 1995 |
| 205.142.0.0/22 | 1k | ARIN | US | 21st Feb 1995 |
| 205.142.100.0/22 | 1k | ARIN | US | 1st Aug 1995 |
| 205.142.104.0/22 | 1k | ARIN | US | 2nd Aug 1995 |
| 205.142.12.0/23 | 512 | ARIN | US | 23rd Feb 1995 |
| 205.142.120.0/22 | 1k | ARIN | US | 3rd Aug 1995 |
| 205.142.124.0/22 | 1k | ARIN | US | 7th Aug 1995 |
| 205.142.132.0/22 | 1k | ARIN | US | 11th Aug 1995 |
| 205.142.136.0/22 | 1k | ARIN | US | 14th Aug 1995 |
| 205.142.144.0/22 | 1k | ARIN | US | 14th Aug 1995 |
| 205.142.152.0/22 | 1k | ARIN | US | 17th Aug 1995 |
| 205.142.156.0/22 | 1k | ARIN | US | 18th Aug 1995 |