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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
85,458 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 204.32.192.0/19 | 8.2k | ARIN |  US | 12th May 1994 |
| 204.33.144.0/20 | 4.1k | ARIN | US | 12th May 1994 |
| 204.44.0.0/20 | 4.1k | ARIN | US | 24th May 1994 |
| 204.44.144.0/21 | 2k | ARIN | US | 27th Dec 1994 |
| 204.44.152.0/22 | 1k | ARIN | US | 27th Dec 1994 |
| 204.44.156.0/24 | 256 | ARIN | US | 27th Dec 1994 |
| 204.44.157.0/24 | 256 | ARIN | US | 25th Jul 2011 |
| 204.44.208.0/20 | 4.1k | ARIN | US | 7th Feb 1995 |
| 204.44.224.0/20 | 4.1k | ARIN | US | 16th Feb 1995 |
| 204.44.32.0/20 | 4.1k | ARIN | US | 18th May 1994 |
| 204.44.48.0/21 | 2k | ARIN | US | 18th May 1994 |
| 204.44.56.0/24 | 256 | ARIN | US | 18th May 1994 |
| 204.44.58.0/23 | 512 | ARIN | US | 2nd Sept 2011 |
| 204.48.116.0/22 | 1k | ARIN | US | 2nd Jul 2025 |
| 204.48.126.0/24 | 256 | ARIN | US | 24th Apr 2020 |
| 204.48.32.0/23 | 512 | RIPE NCC |  CH | 7th Nov 2019 |
| 204.48.34.0/24 | 256 | ARIN | US | 25th Jul 2011 |
| 204.48.40.0/24 | 256 | ARIN | US | 21st Sept 2021 |
| 204.48.46.0/24 | 256 | ARIN | US | 29th Jul 2011 |
| 204.48.47.0/24 | 256 | ARIN | US | 17th Jun 2021 |
| 204.48.52.0/24 | 256 | ARIN | US | 21st Sept 2021 |
| 204.48.8.0/21 | 2k | ARIN | US | 28th Jun 2021 |
| 204.52.132.0/24 | 256 | ARIN | US | 5th Jul 1994 |
| 204.52.133.0/24 | 256 | ARIN | US | 5th Jul 1994 |
| 204.52.134.0/24 | 256 | ARIN | US | 5th Jul 1994 |
| 204.52.136.0/24 | 256 | ARIN | US | 5th Jul 1994 |
| 204.52.139.0/24 | 256 | ARIN | US | 5th Jul 1994 |
| 204.52.140.0/24 | 256 | ARIN | US | 5th Jul 1994 |
| 204.52.141.0/24 | 256 | ARIN | US | 5th Jul 1994 |
| 204.52.143.0/24 | 256 | ARIN | US | 5th Jul 1994 |
| 204.52.144.0/24 | 256 | ARIN | US | 5th Jul 1994 |
| 204.52.146.0/24 | 256 | ARIN | US | 5th Jul 1994 |
| 204.52.147.0/24 | 256 | ARIN | US | 6th Jul 1994 |
| 204.52.148.0/22 | 1k | ARIN | US | 6th Jul 1994 |
| 204.52.152.0/24 | 256 | ARIN | US | 6th Jul 1994 |
| 204.52.153.0/24 | 256 | ARIN | US | 6th Jul 1994 |
| 204.52.154.0/24 | 256 | ARIN | US | 6th Jul 1994 |
| 204.52.156.0/24 | 256 | ARIN | US | 6th Jul 1994 |
| 204.52.157.0/24 | 256 | ARIN | US | 6th Jul 1994 |
| 204.52.158.0/23 | 512 | ARIN | US | 6th Jul 1994 |
| 204.52.166.0/24 | 256 | ARIN | US | 6th Jul 1994 |
| 204.52.168.0/22 | 1k | ARIN | US | 6th Jul 1994 |
| 204.52.172.0/24 | 256 | ARIN | US | 6th Jul 1994 |
| 204.52.173.0/24 | 256 | ARIN | US | 6th Jul 1994 |
| 204.52.175.0/24 | 256 | ARIN | US | 6th Jul 1994 |
| 204.52.178.0/24 | 256 | ARIN | US | 6th Jul 1994 |
| 204.52.180.0/22 | 1k | ARIN | US | 6th Jul 1994 |
| 204.52.184.0/24 | 256 | ARIN | US | 6th Jul 1994 |
| 204.52.185.0/24 | 256 | ARIN | US | 7th Jul 1994 |
| 204.52.186.0/24 | 256 | ARIN | US | 7th Jul 1994 |