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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
85,124 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 192.151.122.0/23 | 512 | ARIN |  US | 26th Mar 1992 |
| 192.151.124.0/22 | 1k | ARIN | US | 26th Mar 1992 |
| 192.151.128.0/24 | 256 | ARIN | US | 26th Mar 1992 |
| 192.151.13.0/24 | 256 | ARIN | US | 26th Mar 1992 |
| 192.151.14.0/23 | 512 | ARIN | US | 26th Mar 1992 |
| 192.151.16.0/24 | 256 | ARIN | US | 26th Mar 1992 |
| 192.151.17.0/24 | 256 | ARIN | US | 26th Mar 1992 |
| 192.151.18.0/23 | 512 | ARIN | US | 26th Mar 1992 |
| 192.151.2.0/23 | 512 | ARIN | US | 26th Mar 1992 |
| 192.151.20.0/24 | 256 | ARIN | US | 26th Mar 1992 |
| 192.151.21.0/24 | 256 | ARIN | US | 26th Mar 1992 |
| 192.151.22.0/24 | 256 | ARIN | US | 26th Mar 1992 |
| 192.151.23.0/24 | 256 | ARIN | US | 26th Mar 1992 |
| 192.151.24.0/23 | 512 | ARIN | US | 26th Mar 1992 |
| 192.151.26.0/23 | 512 | ARIN | US | 26th Mar 1992 |
| 192.151.30.0/23 | 512 | ARIN | US | 26th Mar 1992 |
| 192.151.32.0/24 | 256 | ARIN | US | 26th Mar 1992 |
| 192.151.33.0/24 | 256 | ARIN | US | 26th Mar 1992 |
| 192.151.34.0/23 | 512 | ARIN | US | 26th Mar 1992 |
| 192.151.4.0/24 | 256 | ARIN | US | 26th Mar 1992 |
| 192.151.40.0/24 | 256 | ARIN | US | 26th Mar 1992 |
| 192.151.41.0/24 | 256 | ARIN | US | 26th Mar 1992 |
| 192.151.42.0/23 | 512 | ARIN | US | 26th Mar 1992 |
| 192.151.44.0/23 | 512 | ARIN | US | 26th Mar 1992 |
| 192.151.46.0/23 | 512 | ARIN | US | 26th Mar 1992 |
| 192.151.48.0/23 | 512 | ARIN | US | 26th Mar 1992 |
| 192.151.50.0/23 | 512 | ARIN | US | 26th Mar 1992 |
| 192.151.52.0/24 | 256 | ARIN | US | 26th Mar 1992 |
| 192.151.53.0/24 | 256 | ARIN | US | 26th Mar 1992 |
| 192.151.54.0/23 | 512 | ARIN | US | 26th Mar 1992 |
| 192.151.56.0/23 | 512 | ARIN | US | 26th Mar 1992 |
| 192.151.58.0/24 | 256 | ARIN | US | 26th Mar 1992 |
| 192.151.59.0/24 | 256 | ARIN | US | 26th Mar 1992 |
| 192.151.6.0/23 | 512 | ARIN | US | 26th Mar 1992 |
| 192.151.60.0/23 | 512 | ARIN | US | 26th Mar 1992 |
| 192.151.62.0/24 | 256 | ARIN | US | 26th Mar 1992 |
| 192.151.63.0/24 | 256 | ARIN | US | 26th Mar 1992 |
| 192.151.64.0/24 | 256 | ARIN | US | 26th Mar 1992 |
| 192.151.65.0/24 | 256 | ARIN | US | 26th Mar 1992 |
| 192.151.66.0/24 | 256 | ARIN | US | 26th Mar 1992 |
| 192.151.67.0/24 | 256 | ARIN | US | 26th Mar 1992 |
| 192.151.68.0/24 | 256 | ARIN | US | 26th Mar 1992 |
| 192.151.69.0/24 | 256 | ARIN | US | 26th Mar 1992 |
| 192.151.70.0/23 | 512 | ARIN | US | 26th Mar 1992 |
| 192.151.72.0/24 | 256 | ARIN | US | 26th Mar 1992 |
| 192.151.73.0/24 | 256 | ARIN | US | 26th Mar 1992 |
| 192.151.74.0/23 | 512 | ARIN | US | 26th Mar 1992 |
| 192.151.76.0/22 | 1k | ARIN | US | 26th Mar 1992 |
| 192.151.8.0/23 | 512 | ARIN | US | 26th Mar 1992 |
| 192.151.80.0/24 | 256 | ARIN | US | 26th Mar 1992 |