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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
26,283 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 192.138.136.0/24 | 256 | ARIN |  US | 7th Jan 1992 |
| 192.138.138.0/24 | 256 | ARIN | US | 8th Jan 1992 |
| 192.138.139.0/24 | 256 | ARIN | US | 8th Jan 1992 |
| 192.138.140.0/24 | 256 | ARIN | US | 8th Jan 1992 |
| 192.138.141.0/24 | 256 | ARIN | US | 8th Jan 1992 |
| 192.138.142.0/24 | 256 | ARIN | US | 8th Jan 1992 |
| 192.138.143.0/24 | 256 | ARIN | US | 8th Jan 1992 |
| 192.138.144.0/24 | 256 | ARIN | US | 8th Jan 1992 |
| 192.138.145.0/24 | 256 | ARIN | US | 8th Jan 1992 |
| 192.138.146.0/24 | 256 | ARIN | US | 8th Jan 1992 |
| 192.138.147.0/24 | 256 | ARIN | US | 8th Jan 1992 |
| 192.138.149.0/24 | 256 | ARIN | US | 8th Jan 1992 |
| 192.138.150.0/24 | 256 | ARIN | US | 8th Jan 1992 |
| 192.138.151.0/24 | 256 | ARIN | US | 8th Jan 1992 |
| 192.138.152.0/24 | 256 | ARIN | US | 8th Jan 1992 |
| 192.138.154.0/24 | 256 | ARIN | US | 8th Jan 1992 |
| 192.138.159.0/24 | 256 | ARIN | US | 8th Jan 1992 |
| 192.138.163.0/24 | 256 | ARIN | US | 12th Jul 2019 |
| 192.138.164.0/24 | 256 | ARIN | US | 8th Oct 2021 |
| 192.138.166.0/24 | 256 | ARIN | US | 10th Jan 1992 |
| 192.138.167.0/24 | 256 | ARIN | US | 10th Jan 1992 |
| 192.138.169.0/24 | 256 | ARIN | US | 10th Jan 1992 |
| 192.138.170.0/24 | 256 | ARIN | US | 10th Jan 1992 |
| 192.138.171.0/24 | 256 | ARIN | US | 10th Jan 1992 |
| 192.138.173.0/24 | 256 | ARIN | US | 13th Jan 1992 |
| 192.138.175.0/24 | 256 | ARIN | US | 13th Jan 1992 |
| 192.138.179.0/24 | 256 | ARIN | US | 13th Jan 1992 |
| 192.138.180.0/24 | 256 | ARIN | US | 13th Jan 1992 |
| 192.138.181.0/24 | 256 | ARIN | US | 14th Jan 1992 |
| 192.138.184.0/24 | 256 | ARIN | US | 14th Jan 1992 |
| 192.138.190.0/24 | 256 | ARIN | US | 14th Jan 1992 |
| 192.138.195.0/24 | 256 | ARIN | US | 15th Jan 1992 |
| 192.138.196.0/24 | 256 | ARIN | US | 15th Jan 1992 |
| 192.138.197.0/24 | 256 | ARIN | US | 15th Jan 1992 |
| 192.138.198.0/24 | 256 | ARIN | US | 16th Jan 1992 |
| 192.138.199.0/24 | 256 | ARIN | US | 16th Jan 1992 |
| 192.138.200.0/24 | 256 | ARIN | US | 16th Jan 1992 |
| 192.138.202.0/24 | 256 | ARIN | US | 16th Jan 1992 |
| 192.138.206.0/24 | 256 | ARIN | US | 29th Jun 2023 |
| 192.138.207.0/24 | 256 | ARIN | US | 3rd Feb 1992 |
| 192.138.208.0/24 | 256 | ARIN | US | 26th Feb 1992 |
| 192.138.212.0/24 | 256 | ARIN | US | 3rd Jun 2015 |
| 192.138.215.0/24 | 256 | ARIN | US | 3rd Mar 1996 |
| 192.138.216.0/24 | 256 | ARIN | US | 3rd Apr 1992 |
| 192.138.217.0/24 | 256 | ARIN | US | 4th May 1992 |
| 192.138.218.0/23 | 512 | ARIN | US | 18th Feb 2015 |
| 192.138.221.0/24 | 256 | ARIN | US | 28th May 1992 |
| 192.138.222.0/24 | 256 | ARIN | US | 28th May 1992 |
| 192.138.223.0/24 | 256 | ARIN | US | 28th May 1992 |
| 192.138.224.0/24 | 256 | ARIN | US | 28th May 1992 |