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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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 |
|---|---|---|---|---|
| 192.156.194.0/24 | 256 | ARIN |  US | 28th Apr 1992 |
| 192.156.195.0/24 | 256 | ARIN | US | 28th Apr 1992 |
| 192.156.196.0/24 | 256 | ARIN | US | 24th Jun 2015 |
| 192.156.197.0/24 | 256 | ARIN | US | 12th May 1992 |
| 192.156.198.0/24 | 256 | ARIN | US | 29th Apr 1992 |
| 192.156.200.0/24 | 256 | ARIN | US | 29th Apr 1992 |
| 192.156.201.0/24 | 256 | ARIN | US | 29th Apr 1992 |
| 192.156.203.0/24 | 256 | ARIN | US | 29th Apr 1992 |
| 192.156.204.0/24 | 256 | ARIN | US | 29th Apr 1992 |
| 192.156.206.0/24 | 256 | ARIN | US | 29th Apr 1992 |
| 192.156.209.0/24 | 256 | ARIN | US | 30th Apr 1992 |
| 192.156.212.0/24 | 256 | ARIN | US | 30th Apr 1992 |
| 192.156.216.0/24 | 256 | ARIN | US | 13th Feb 2020 |
| 192.156.221.0/24 | 256 | ARIN | US | 5th May 1992 |
| 192.156.222.0/24 | 256 | ARIN | US | 5th May 1992 |
| 192.156.223.0/24 | 256 | ARIN | US | 5th May 1992 |
| 192.156.224.0/24 | 256 | ARIN | US | 5th May 1992 |
| 192.156.226.0/24 | 256 | ARIN | US | 8th May 1992 |
| 192.156.229.0/24 | 256 | ARIN | US | 8th May 1992 |
| 192.156.231.0/24 | 256 | ARIN | US | 7th Mar 1996 |
| 192.156.241.0/24 | 256 | ARIN | US | 28th May 1992 |
| 192.156.242.0/24 | 256 | ARIN | US | 28th May 1992 |
| 192.156.243.0/24 | 256 | ARIN | US | 28th May 1992 |
| 192.156.250.0/24 | 256 | ARIN | US | 1st Jun 1992 |
| 192.156.253.0/24 | 256 | ARIN | US | 9th Jun 1992 |
| 192.156.254.0/24 | 256 | ARIN | US | 10th Jun 1992 |
| 192.156.97.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.156.98.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.156.99.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.157.128.0/24 | 256 | ARIN | US | 14th Feb 1995 |
| 192.157.163.0/24 | 256 | ARIN | US | 14th Feb 1995 |
| 192.157.175.0/24 | 256 | ARIN | US | 14th Feb 1995 |
| 192.157.177.0/24 | 256 | ARIN | US | 14th Feb 1995 |
| 192.157.184.0/24 | 256 | ARIN | US | 14th Feb 1995 |
| 192.157.186.0/24 | 256 | ARIN | US | 14th Feb 1995 |
| 192.157.188.0/24 | 256 | ARIN | US | 14th Feb 1995 |
| 192.157.31.0/24 | 256 | ARIN | US | 26th May 1992 |
| 192.157.38.0/24 | 256 | ARIN | US | 16th Apr 1992 |
| 192.157.4.0/24 | 256 | ARIN | US | 15th Apr 1992 |
| 192.157.6.0/23 | 512 | ARIN | US | 4th Mar 2015 |
| 192.158.1.0/24 | 256 | ARIN | US | 20th Apr 1992 |
| 192.158.104.0/22 | 1k | ARIN | US | 21st Apr 1992 |
| 192.158.108.0/24 | 256 | ARIN | US | 22nd Apr 2026 |
| 192.158.109.0/24 | 256 | ARIN | US | 21st Apr 1992 |
| 192.158.112.0/22 | 1k | ARIN | US | 21st Apr 1992 |
| 192.158.116.0/23 | 512 | ARIN | US | 21st Apr 1992 |
| 192.158.120.0/21 | 2k | ARIN | US | 21st Apr 1992 |
| 192.158.128.0/21 | 2k | ARIN | US | 21st Apr 1992 |
| 192.158.136.0/22 | 1k | ARIN | US | 21st Apr 1992 |
| 192.158.142.0/24 | 256 | ARIN | US | 21st Apr 1992 |