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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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 unannounced space registered through ARIN, largest first.
Unannounced blocks in United States
26,289 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 192.155.128.0/20 | 4.1k | ARIN |  US | 20th Apr 1992 |
| 192.155.144.0/21 | 2k | ARIN | US | 20th Apr 1992 |
| 192.155.152.0/22 | 1k | ARIN | US | 20th Apr 1992 |
| 192.155.156.0/23 | 512 | ARIN | US | 20th Apr 1992 |
| 192.155.16.0/20 | 4.1k | ARIN | US | 9th Apr 1992 |
| 192.155.192.0/18 | 16.4k | ARIN | US | 16th Jan 2013 |
| 192.155.32.0/19 | 8.2k | ARIN | US | 9th Apr 1992 |
| 192.155.64.0/22 | 1k | ARIN | US | 9th Apr 1992 |
| 192.155.68.0/24 | 256 | ARIN | US | 9th Apr 1992 |
| 192.155.8.0/24 | 256 | ARIN | US | 8th Jul 2015 |
| 192.155.9.0/24 | 256 | ARIN | US | 9th Apr 1992 |
| 192.156.103.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.156.104.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.156.105.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.156.107.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.156.108.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.156.112.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.156.113.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.156.115.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.156.116.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.156.117.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.156.118.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.156.119.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.156.120.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.156.121.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.156.123.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.156.125.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.156.126.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.156.127.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.156.128.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.156.129.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.156.130.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.156.131.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.156.135.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.156.136.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.156.137.0/24 | 256 | ARIN | US | 16th Apr 1992 |
| 192.156.138.0/24 | 256 | ARIN | US | 16th Apr 1992 |
| 192.156.139.0/24 | 256 | ARIN | US | 16th Apr 1992 |
| 192.156.160.0/24 | 256 | ARIN | US | 20th Apr 1992 |
| 192.156.161.0/24 | 256 | ARIN | US | 20th Apr 1992 |
| 192.156.163.0/24 | 256 | ARIN | US | 20th Apr 1992 |
| 192.156.166.0/24 | 256 | ARIN | US | 21st Apr 1992 |
| 192.156.168.0/24 | 256 | ARIN | US | 21st Apr 1992 |
| 192.156.170.0/23 | 512 | ARIN | US | 25th Sept 1992 |
| 192.156.172.0/22 | 1k | ARIN | US | 25th Sept 1992 |
| 192.156.176.0/21 | 2k | ARIN | US | 25th Sept 1992 |
| 192.156.184.0/22 | 1k | ARIN | US | 25th Sept 1992 |
| 192.156.188.0/23 | 512 | ARIN | US | 25th Sept 1992 |
| 192.156.192.0/24 | 256 | ARIN | US | 28th Apr 1992 |
| 192.156.193.0/24 | 256 | ARIN | US | 28th Apr 1992 |