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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
Browse by country
Countries with unannounced space registered through ARIN, largest first.
Unannounced blocks registered through ARIN
30,479 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 199.166.38.0/24 | 256 | ARIN |  CA | 2nd Feb 1994 |
| 199.166.39.0/24 | 256 | ARIN | CA | 2nd Feb 1994 |
| 199.166.4.0/24 | 256 | ARIN | CA | 2nd Feb 1994 |
| 199.166.40.0/21 | 2k | ARIN | CA | 2nd Feb 1994 |
| 199.166.48.0/20 | 4.1k | ARIN | CA | 2nd Feb 1994 |
| 199.166.7.0/24 | 256 | ARIN | CA | 2nd Feb 1994 |
| 199.167.0.0/21 | 2k | ARIN |  US | 22nd Apr 1994 |
| 199.167.168.0/22 | 1k | ARIN | US | 8th Jun 2011 |
| 199.167.172.0/22 | 1k | ARIN | US | 8th Jun 2011 |
| 199.167.188.0/23 | 512 | ARIN | US | 17th Dec 2025 |
| 199.167.190.0/24 | 256 | ARIN | US | 17th Dec 2025 |
| 199.167.242.0/24 | 256 | ARIN | US | 16th Jun 2011 |
| 199.168.13.0/24 | 256 | ARIN | US | 31st Mar 2009 |
| 199.168.132.0/22 | 1k | ARIN | US | 8th Oct 2025 |
| 199.168.14.0/24 | 256 | ARIN | US | 31st Mar 2009 |
| 199.168.228.0/22 | 1k | ARIN | US | 8th Feb 2022 |
| 199.168.25.0/24 | 256 | ARIN | US | 24th Jul 2012 |
| 199.168.252.0/22 | 1k | ARIN | US | 28th Jun 2011 |
| 199.168.40.0/24 | 256 | ARIN | US | 15th Feb 1994 |
| 199.175.1.0/24 | 256 | ARIN | CA | 16th Feb 1994 |
| 199.175.10.0/23 | 512 | ARIN | CA | 10th Mar 1994 |
| 199.175.100.0/24 | 256 | ARIN | CA | 14th Feb 1994 |
| 199.175.104.0/24 | 256 | ARIN | CA | 16th Feb 1994 |
| 199.175.105.0/24 | 256 | ARIN | CA | 30th Aug 1994 |
| 199.175.108.0/24 | 256 | ARIN | CA | 16th Feb 1994 |
| 199.175.109.0/24 | 256 | ARIN | CA | 16th Feb 1994 |
| 199.175.110.0/23 | 512 | ARIN | US | 16th Feb 1994 |
| 199.175.12.0/22 | 1k | ARIN | CA | 10th Mar 1994 |
| 199.175.120.0/22 | 1k | ARIN | US | 16th Feb 1994 |
| 199.175.136.0/24 | 256 | ARIN | CA | 16th Feb 1994 |
| 199.175.137.0/24 | 256 | ARIN | CA | 16th Feb 1994 |
| 199.175.140.0/24 | 256 | ARIN | CA | 16th Feb 1994 |
| 199.175.141.0/24 | 256 | ARIN | CA | 16th Feb 1994 |
| 199.175.142.0/23 | 512 | ARIN | CA | 16th Feb 1994 |
| 199.175.144.0/21 | 2k | ARIN | CA | 16th Feb 1994 |
| 199.175.152.0/22 | 1k | ARIN | CA | 16th Feb 1994 |
| 199.175.156.0/24 | 256 | ARIN | CA | 16th Feb 1994 |
| 199.175.158.0/23 | 512 | ARIN | CA | 16th Feb 1994 |
| 199.175.170.0/23 | 512 | ARIN | CA | 16th Feb 1994 |
| 199.175.172.0/22 | 1k | ARIN | CA | 16th Feb 1994 |
| 199.175.176.0/22 | 1k | ARIN | CA | 16th Feb 1994 |
| 199.175.189.0/24 | 256 | ARIN | CA | 16th Feb 1994 |
| 199.175.190.0/23 | 512 | ARIN | CA | 16th Feb 1994 |
| 199.175.192.0/21 | 2k | ARIN | CA | 16th Feb 1994 |
| 199.175.2.0/24 | 256 | ARIN | CA | 16th Feb 1994 |
| 199.175.225.0/24 | 256 | ARIN | CA | 20th Feb 1997 |
| 199.175.226.0/23 | 512 | ARIN | CA | 22nd Jun 1994 |
| 199.175.228.0/24 | 256 | ARIN | CA | 22nd Jun 1994 |
| 199.175.229.0/24 | 256 | ARIN | CA | 23rd Jun 1994 |
| 199.175.230.0/24 | 256 | ARIN | CA | 19th Mar 1997 |