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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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 the most unannounced blocks, largest first.
Unannounced blocks in United States
27,014 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 192.231.156.0/22 | 1k | ARIN |  US | 9th Oct 1992 |
| 192.231.161.0/24 | 256 | ARIN | US | 12th Oct 1992 |
| 192.231.165.0/24 | 256 | ARIN | US | 13th Oct 1992 |
| 192.231.180.0/24 | 256 | ARIN | US | 13th Oct 1992 |
| 192.231.181.0/24 | 256 | ARIN | US | 15th Oct 1992 |
| 192.231.182.0/24 | 256 | ARIN | US | 15th Oct 1992 |
| 192.231.184.0/24 | 256 | ARIN | US | 15th Oct 1992 |
| 192.231.185.0/24 | 256 | ARIN | US | 15th Oct 1992 |
| 192.231.186.0/24 | 256 | ARIN | US | 15th Oct 1992 |
| 192.231.187.0/24 | 256 | ARIN | US | 15th Oct 1992 |
| 192.231.189.0/24 | 256 | ARIN | US | 15th Oct 1992 |
| 192.231.190.0/24 | 256 | ARIN | US | 15th Oct 1992 |
| 192.231.194.0/24 | 256 | ARIN | US | 15th Oct 1992 |
| 192.231.195.0/24 | 256 | ARIN | US | 16th Oct 1992 |
| 192.231.196.0/24 | 256 | ARIN | US | 16th Oct 1992 |
| 192.231.197.0/24 | 256 | ARIN | US | 16th Oct 1992 |
| 192.231.200.0/24 | 256 | ARIN | US | 16th Oct 1992 |
| 192.231.204.0/24 | 256 | ARIN | US | 16th Oct 1992 |
| 192.231.205.0/24 | 256 | ARIN | US | 16th Oct 1992 |
| 192.231.206.0/24 | 256 | ARIN | US | 16th Oct 1992 |
| 192.231.208.0/24 | 256 | ARIN | US | 2nd Jul 2026 |
| 192.231.209.0/24 | 256 | ARIN | US | 20th Oct 1992 |
| 192.231.210.0/24 | 256 | ARIN | US | 20th Oct 1992 |
| 192.231.217.0/24 | 256 | ARIN | US | 22nd Oct 1992 |
| 192.231.221.0/24 | 256 | ARIN | US | 22nd Oct 1992 |
| 192.231.222.0/24 | 256 | ARIN | US | 22nd Oct 1992 |
| 192.231.223.0/24 | 256 | ARIN | US | 22nd Oct 1992 |
| 192.231.224.0/22 | 1k | ARIN | US | 22nd Oct 1992 |
| 192.231.228.0/23 | 512 | ARIN | US | 22nd Oct 1992 |
| 192.231.232.0/24 | 256 | ARIN | US | 22nd Oct 1992 |
| 192.231.235.0/24 | 256 | ARIN | US | 22nd Oct 1992 |
| 192.231.236.0/24 | 256 | ARIN | US | 22nd Oct 1992 |
| 192.231.239.0/24 | 256 | ARIN | US | 22nd Oct 1992 |
| 192.231.240.0/24 | 256 | ARIN | US | 22nd Oct 1992 |
| 192.231.241.0/24 | 256 | ARIN | US | 22nd Oct 1992 |
| 192.231.242.0/24 | 256 | ARIN | US | 22nd Oct 1992 |
| 192.231.245.0/24 | 256 | ARIN | US | 22nd Oct 1992 |
| 192.231.250.0/23 | 512 | ARIN | US | 6th May 2015 |
| 192.231.252.0/24 | 256 | ARIN | US | 26th Oct 1992 |
| 192.231.27.0/24 | 256 | ARIN | US | 22nd Sept 1992 |
| 192.231.28.0/24 | 256 | ARIN | US | 22nd Sept 1992 |
| 192.231.3.0/24 | 256 | ARIN | US | 21st Sept 1992 |
| 192.231.31.0/24 | 256 | ARIN | US | 23rd Sept 1992 |
| 192.231.32.0/24 | 256 | ARIN | US | 23rd Sept 1992 |
| 192.231.37.0/24 | 256 | ARIN | US | 23rd Sept 1992 |
| 192.231.38.0/24 | 256 | ARIN | US | 23rd Sept 1992 |
| 192.231.4.0/24 | 256 | ARIN | US | 21st Sept 1992 |
| 192.231.42.0/24 | 256 | ARIN | US | 24th Sept 1992 |
| 192.231.44.0/24 | 256 | ARIN | US | 25th Sept 1992 |
| 192.231.45.0/24 | 256 | ARIN | US | 25th Sept 1992 |