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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
85,392 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 205.166.187.0/24 | 256 | ARIN |  US | 11th Apr 1995 |
| 205.166.188.0/24 | 256 | ARIN | US | 11th Apr 1995 |
| 205.166.189.0/24 | 256 | ARIN | US | 11th Apr 1995 |
| 205.166.19.0/24 | 256 | ARIN | US | 21st Mar 1995 |
| 205.166.190.0/24 | 256 | ARIN | US | 11th Apr 1995 |
| 205.166.191.0/24 | 256 | ARIN | US | 11th Apr 1995 |
| 205.166.192.0/24 | 256 | ARIN | US | 11th Apr 1995 |
| 205.166.193.0/24 | 256 | ARIN | US | 11th Apr 1995 |
| 205.166.194.0/24 | 256 | ARIN | US | 11th Apr 1995 |
| 205.166.196.0/24 | 256 | ARIN | US | 11th Apr 1995 |
| 205.166.197.0/24 | 256 | ARIN | US | 11th Apr 1995 |
| 205.166.198.0/24 | 256 | ARIN | US | 11th Apr 1995 |
| 205.166.199.0/24 | 256 | ARIN | US | 11th Apr 1995 |
| 205.166.2.0/24 | 256 | ARIN | US | 17th Mar 1995 |
| 205.166.200.0/24 | 256 | ARIN | US | 12th Apr 1995 |
| 205.166.201.0/24 | 256 | ARIN | US | 12th Apr 1995 |
| 205.166.202.0/24 | 256 | ARIN | US | 12th Apr 1995 |
| 205.166.203.0/24 | 256 | ARIN | US | 12th Apr 1995 |
| 205.166.204.0/24 | 256 | ARIN | US | 13th Apr 1995 |
| 205.166.206.0/24 | 256 | ARIN | US | 13th Apr 1995 |
| 205.166.207.0/24 | 256 | ARIN | US | 13th Apr 1995 |
| 205.166.208.0/24 | 256 | ARIN | US | 13th Apr 1995 |
| 205.166.209.0/24 | 256 | ARIN | US | 13th Apr 1995 |
| 205.166.210.0/24 | 256 | ARIN | US | 13th Apr 1995 |
| 205.166.211.0/24 | 256 | ARIN | US | 13th Apr 1995 |
| 205.166.212.0/24 | 256 | ARIN | US | 13th Apr 1995 |
| 205.166.213.0/24 | 256 | ARIN | US | 13th Apr 1995 |
| 205.166.215.0/24 | 256 | ARIN | US | 13th Apr 1995 |
| 205.166.217.0/24 | 256 | ARIN | US | 13th Apr 1995 |
| 205.166.218.0/24 | 256 | ARIN | US | 13th Apr 1995 |
| 205.166.219.0/24 | 256 | ARIN | US | 13th Apr 1995 |
| 205.166.220.0/24 | 256 | ARIN | US | 13th Apr 1995 |
| 205.166.221.0/24 | 256 | ARIN | US | 13th Apr 1995 |
| 205.166.222.0/24 | 256 | ARIN | US | 14th Apr 1995 |
| 205.166.223.0/24 | 256 | ARIN | US | 18th Apr 1995 |
| 205.166.224.0/24 | 256 | ARIN | US | 18th Apr 1995 |
| 205.166.225.0/24 | 256 | ARIN | US | 18th Apr 1995 |
| 205.166.227.0/24 | 256 | ARIN | US | 18th Apr 1995 |
| 205.166.228.0/24 | 256 | ARIN | US | 18th Apr 1995 |
| 205.166.229.0/24 | 256 | ARIN | US | 18th Apr 1995 |
| 205.166.23.0/24 | 256 | ARIN | US | 21st Mar 1995 |
| 205.166.232.0/24 | 256 | ARIN | US | 20th Apr 1995 |
| 205.166.233.0/24 | 256 | ARIN | US | 20th Apr 1995 |
| 205.166.234.0/24 | 256 | ARIN | US | 20th Apr 1995 |
| 205.166.235.0/24 | 256 | ARIN | US | 8th Jun 2026 |
| 205.166.236.0/24 | 256 | ARIN | US | 20th Apr 1995 |
| 205.166.237.0/24 | 256 | ARIN | US | 20th Apr 1995 |
| 205.166.238.0/24 | 256 | ARIN | US | 20th Apr 1995 |
| 205.166.239.0/24 | 256 | ARIN | US | 20th Apr 1995 |
| 205.166.24.0/24 | 256 | ARIN | US | 21st Mar 1995 |