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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
85,201 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 192.251.24.0/24 | 256 | ARIN |  US | 18th Nov 1992 |
| 192.251.25.0/24 | 256 | ARIN | US | 18th Nov 1992 |
| 192.251.29.0/24 | 256 | ARIN |  CA | 18th Nov 1992 |
| 192.251.3.0/24 | 256 | ARIN | US | 9th Nov 1992 |
| 192.251.30.0/24 | 256 | ARIN | CA | 18th Nov 1992 |
| 192.251.31.0/24 | 256 | ARIN | US | 18th Nov 1992 |
| 192.251.33.0/24 | 256 | ARIN | US | 23rd Jan 1995 |
| 192.251.35.0/24 | 256 | ARIN | US | 18th Nov 1992 |
| 192.251.36.0/24 | 256 | ARIN | US | 18th Nov 1992 |
| 192.251.38.0/24 | 256 | ARIN | US | 19th Nov 1992 |
| 192.251.39.0/24 | 256 | LACNIC |  CL | 20th Nov 1992 |
| 192.251.4.0/24 | 256 | ARIN | US | 6th Nov 1992 |
| 192.251.40.0/24 | 256 | ARIN | US | 20th Nov 1992 |
| 192.251.41.0/24 | 256 | ARIN | US | 20th Nov 1992 |
| 192.251.42.0/24 | 256 | ARIN | US | 20th Nov 1992 |
| 192.251.43.0/24 | 256 | ARIN | US | 24th Nov 1992 |
| 192.251.44.0/24 | 256 | ARIN | US | 24th Nov 1992 |
| 192.251.45.0/24 | 256 | ARIN | US | 24th Nov 1992 |
| 192.251.49.0/24 | 256 | ARIN | US | 24th Nov 1992 |
| 192.251.5.0/24 | 256 | ARIN | US | 6th Nov 1992 |
| 192.251.50.0/24 | 256 | ARIN | US | 24th Nov 1992 |
| 192.251.52.0/24 | 256 | ARIN | CA | 24th Nov 1992 |
| 192.251.53.0/24 | 256 | ARIN | CA | 24th Nov 1992 |
| 192.251.54.0/24 | 256 | ARIN | CA | 24th Nov 1992 |
| 192.251.55.0/24 | 256 | ARIN | CA | 24th Nov 1992 |
| 192.251.59.0/24 | 256 | ARIN | US | 24th Nov 1992 |
| 192.251.6.0/24 | 256 | ARIN | US | 6th Nov 1992 |
| 192.251.60.0/24 | 256 | ARIN | US | 24th Nov 1992 |
| 192.251.66.0/24 | 256 | ARIN | US | 24th Nov 1992 |
| 192.251.67.0/24 | 256 | ARIN | US | 24th Nov 1992 |
| 192.251.68.0/24 | 256 | ARIN | US | 24th Nov 1992 |
| 192.251.7.0/24 | 256 | ARIN | US | 6th Nov 1992 |
| 192.251.70.0/24 | 256 | ARIN | US | 24th Nov 1992 |
| 192.251.71.0/24 | 256 | ARIN | US | 24th Nov 1992 |
| 192.251.72.0/24 | 256 | ARIN | US | 24th Nov 1992 |
| 192.251.76.0/24 | 256 | ARIN | US | 24th Nov 1992 |
| 192.251.77.0/24 | 256 | ARIN | US | 24th Nov 1992 |
| 192.251.78.0/24 | 256 | ARIN | US | 25th Nov 1992 |
| 192.251.79.0/24 | 256 | ARIN | US | 25th Nov 1992 |
| 192.251.8.0/24 | 256 | ARIN | US | 6th Nov 1992 |
| 192.251.80.0/24 | 256 | ARIN | US | 25th Nov 1992 |
| 192.251.81.0/24 | 256 | ARIN | US | 1st Jul 2026 |
| 192.251.84.0/24 | 256 | ARIN | US | 25th Nov 1992 |
| 192.251.85.0/24 | 256 | ARIN | US | 25th Nov 1992 |
| 192.251.86.0/24 | 256 | ARIN | US | 25th Nov 1992 |
| 192.251.88.0/24 | 256 | ARIN | US | 25th Nov 1992 |
| 192.251.89.0/24 | 256 | ARIN | US | 25th Nov 1992 |
| 192.251.9.0/24 | 256 | ARIN | US | 9th Nov 1992 |
| 192.251.90.0/24 | 256 | ARIN | US | 25th Nov 1992 |
| 192.251.91.0/24 | 256 | ARIN | CA | 25th Nov 1992 |