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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
30,430 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 192.101.157.0/24 | 256 | ARIN |  US | 5th Jul 1991 |
| 192.101.158.0/24 | 256 | ARIN | US | 5th Jul 1991 |
| 192.101.159.0/24 | 256 | ARIN | US | 5th Jul 1991 |
| 192.101.169.0/24 | 256 | ARIN |  PR | 11th Jul 1991 |
| 192.101.17.0/24 | 256 | ARIN | US | 16th Apr 1991 |
| 192.101.171.0/24 | 256 | ARIN | US | 11th Jul 1991 |
| 192.101.173.0/24 | 256 | ARIN | US | 12th Sept 1991 |
| 192.101.175.0/24 | 256 | ARIN | US | 12th Jul 1991 |
| 192.101.178.0/24 | 256 | ARIN | US | 16th Jul 1991 |
| 192.101.181.0/24 | 256 | ARIN | US | 16th Jul 1991 |
| 192.101.182.0/24 | 256 | ARIN | US | 16th Jul 1991 |
| 192.101.184.0/24 | 256 | ARIN | US | 16th Jul 1991 |
| 192.101.187.0/24 | 256 | ARIN | US | 16th Jul 1991 |
| 192.101.189.0/24 | 256 | ARIN | US | 16th Jul 1991 |
| 192.101.19.0/24 | 256 | ARIN | US | 16th Apr 1991 |
| 192.101.191.0/24 | 256 | ARIN | US | 19th Jul 1991 |
| 192.101.193.0/24 | 256 | ARIN | US | 19th Jul 1991 |
| 192.101.194.0/24 | 256 | ARIN | US | 19th Jul 1991 |
| 192.101.195.0/24 | 256 | ARIN | US | 19th Jul 1991 |
| 192.101.196.0/24 | 256 | ARIN | US | 19th Jul 1991 |
| 192.101.199.0/24 | 256 | ARIN | US | 18th Mar 2015 |
| 192.101.2.0/24 | 256 | ARIN | US | 11th Mar 1991 |
| 192.101.20.0/24 | 256 | ARIN | US | 16th Apr 1991 |
| 192.101.200.0/21 | 2k | ARIN | US | 19th Jul 1991 |
| 192.101.208.0/20 | 4.1k | ARIN | US | 19th Jul 1991 |
| 192.101.224.0/20 | 4.1k | ARIN | US | 19th Jul 1991 |
| 192.101.240.0/21 | 2k | ARIN | US | 19th Jul 1991 |
| 192.101.248.0/23 | 512 | ARIN | US | 19th Jul 1991 |
| 192.101.25.0/24 | 256 | ARIN | US | 17th Apr 1991 |
| 192.101.253.0/24 | 256 | ARIN | US | 19th Jul 1991 |
| 192.101.26.0/24 | 256 | ARIN | US | 25th Apr 1991 |
| 192.101.27.0/24 | 256 | ARIN | US | 25th Apr 1991 |
| 192.101.29.0/24 | 256 | ARIN | US | 25th Apr 1991 |
| 192.101.3.0/24 | 256 | ARIN | US | 11th Mar 1991 |
| 192.101.30.0/24 | 256 | ARIN | US | 25th Apr 1991 |
| 192.101.31.0/24 | 256 | ARIN | US | 25th Apr 1991 |
| 192.101.35.0/24 | 256 | ARIN | US | 18th Jun 1991 |
| 192.101.36.0/24 | 256 | ARIN | US | 18th Jun 1991 |
| 192.101.37.0/24 | 256 | ARIN | US | 18th Jun 1991 |
| 192.101.38.0/24 | 256 | ARIN | US | 18th Jun 1991 |
| 192.101.39.0/24 | 256 | ARIN | US | 18th Jun 1991 |
| 192.101.40.0/24 | 256 | ARIN | US | 18th Jun 1991 |
| 192.101.41.0/24 | 256 | ARIN | US | 18th Jun 1991 |
| 192.101.44.0/24 | 256 | ARIN | US | 21st Jun 1991 |
| 192.101.45.0/24 | 256 | ARIN | US | 20th Mar 2015 |
| 192.101.46.0/23 | 512 | ARIN |  CA | 1st Oct 2026 |
| 192.101.6.0/24 | 256 | ARIN | US | 11th Mar 1991 |
| 192.101.7.0/24 | 256 | ARIN | US | 11th Mar 1991 |
| 192.101.76.0/24 | 256 | ARIN | US | 21st Jun 1991 |
| 192.101.78.0/24 | 256 | ARIN | US | 21st Jun 1991 |