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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
85,149 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 192.203.186.0/24 | 256 | ARIN |  US | 21st Sept 1992 |
| 192.203.188.0/24 | 256 | ARIN | US | 25th Nov 1995 |
| 192.203.189.0/24 | 256 | ARIN | US | 21st Sept 1992 |
| 192.203.190.0/24 | 256 | ARIN | US | 21st Sept 1992 |
| 192.203.192.0/24 | 256 | ARIN | US | 21st Sept 1992 |
| 192.203.197.0/24 | 256 | ARIN |  CA | 22nd Sept 1992 |
| 192.203.198.0/24 | 256 | ARIN | US | 23rd Sept 1992 |
| 192.203.202.0/24 | 256 | ARIN | US | 23rd Sept 1992 |
| 192.203.203.0/24 | 256 | ARIN | CA | 23rd Sept 1992 |
| 192.203.206.0/24 | 256 | ARIN | US | 30th Sept 1992 |
| 192.203.207.0/24 | 256 | ARIN | US | 30th Sept 1992 |
| 192.203.210.0/24 | 256 | ARIN | US | 30th Sept 1992 |
| 192.203.212.0/24 | 256 | ARIN | US | 9th Oct 1992 |
| 192.203.213.0/24 | 256 | APNIC |  AU | 9th Oct 1992 |
| 192.203.214.0/23 | 512 | ARIN | US | 9th Oct 1992 |
| 192.203.217.0/24 | 256 | ARIN | US | 22nd Oct 1992 |
| 192.203.220.0/24 | 256 | ARIN | US | 26th Oct 1992 |
| 192.203.221.0/24 | 256 | ARIN | US | 26th Oct 1992 |
| 192.203.224.0/24 | 256 | ARIN | US | 6th Jun 1995 |
| 192.203.225.0/24 | 256 | ARIN | US | 28th Oct 1992 |
| 192.203.226.0/24 | 256 | ARIN | US | 29th Oct 1992 |
| 192.203.227.0/24 | 256 | RIPE NCC |  SA | 30th Oct 1992 |
| 192.203.229.0/24 | 256 | ARIN | US | 18th Nov 1992 |
| 192.203.231.0/24 | 256 | ARIN | US | 18th Sept 2015 |
| 192.203.234.0/24 | 256 | ARIN | US | 23rd Nov 1992 |
| 192.203.235.0/24 | 256 | APNIC | AU | 23rd Nov 1992 |
| 192.203.236.0/24 | 256 | ARIN | US | 23rd Nov 1992 |
| 192.203.238.0/24 | 256 | ARIN | US | 23rd Nov 1992 |
| 192.203.239.0/24 | 256 | ARIN | US | 29th Sept 2023 |
| 192.203.240.0/24 | 256 | ARIN | US | 23rd Nov 1992 |
| 192.203.243.0/24 | 256 | ARIN | US | 23rd Nov 1992 |
| 192.203.244.0/24 | 256 | ARIN | US | 23rd Nov 1992 |
| 192.203.245.0/24 | 256 | ARIN | US | 23rd Nov 1992 |
| 192.203.246.0/24 | 256 | ARIN | US | 15th Sept 2022 |
| 192.203.248.0/24 | 256 | ARIN | US | 24th Nov 1992 |
| 192.203.249.0/24 | 256 | ARIN | US | 23rd May 2017 |
| 192.203.250.0/24 | 256 | ARIN | US | 24th Nov 1992 |
| 192.203.251.0/24 | 256 | ARIN | US | 24th Nov 1992 |
| 192.203.252.0/24 | 256 | ARIN | US | 27th Nov 1992 |
| 192.203.42.0/24 | 256 | ARIN | US | 4th Aug 1992 |
| 192.203.43.0/24 | 256 | ARIN | US | 4th Aug 1992 |
| 192.203.44.0/24 | 256 | ARIN | US | 4th Aug 1992 |
| 192.203.45.0/24 | 256 | ARIN | US | 4th Aug 1992 |
| 192.203.46.0/23 | 512 | ARIN | US | 4th Aug 1992 |
| 192.203.6.0/23 | 512 | ARIN | US | 31st Jul 1992 |
| 192.203.64.0/21 | 2k | ARIN | US | 4th Aug 1992 |
| 192.203.72.0/22 | 1k | ARIN | US | 4th Aug 1992 |
| 192.203.76.0/24 | 256 | ARIN | US | 4th Aug 1992 |
| 192.203.77.0/24 | 256 | ARIN | US | 4th Aug 1992 |
| 192.203.78.0/24 | 256 | ARIN | US | 4th Aug 1992 |