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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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 unannounced space registered through ARIN, largest first.
Unannounced blocks in United States
26,300 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 205.142.16.0/22 | 1k | ARIN |  US | 23rd Feb 1995 |
| 205.142.160.0/22 | 1k | ARIN | US | 24th Aug 1995 |
| 205.142.168.0/22 | 1k | ARIN | US | 25th Aug 1995 |
| 205.142.184.0/22 | 1k | ARIN | US | 1st Sept 1995 |
| 205.142.200.0/22 | 1k | ARIN | US | 1st Sept 1995 |
| 205.142.204.0/22 | 1k | ARIN | US | 1st Sept 1995 |
| 205.142.208.0/22 | 1k | ARIN | US | 1st Sept 1995 |
| 205.142.212.0/22 | 1k | ARIN | US | 5th Sept 1995 |
| 205.142.216.0/22 | 1k | ARIN | US | 8th Sept 1995 |
| 205.142.220.0/22 | 1k | ARIN | US | 12th Sept 1995 |
| 205.142.236.0/22 | 1k | ARIN | US | 14th Sept 1995 |
| 205.142.24.0/22 | 1k | ARIN | US | 23rd Feb 1995 |
| 205.142.244.0/22 | 1k | ARIN | US | 20th Sept 1995 |
| 205.142.28.0/22 | 1k | ARIN | US | 27th Feb 1995 |
| 205.142.4.0/23 | 512 | ARIN | US | 21st Feb 1995 |
| 205.142.40.0/22 | 1k | ARIN | US | 3rd Mar 1995 |
| 205.142.44.0/23 | 512 | ARIN | US | 3rd Mar 1995 |
| 205.142.46.0/24 | 256 | ARIN | US | 3rd Mar 1995 |
| 205.142.47.0/24 | 256 | ARIN | US | 1st Mar 2012 |
| 205.142.48.0/22 | 1k | ARIN | US | 19th Jan 2024 |
| 205.142.52.0/22 | 1k | ARIN | US | 4th Mar 1995 |
| 205.142.6.0/24 | 256 | ARIN | US | 21st Feb 1995 |
| 205.142.68.0/22 | 1k | ARIN | US | 18th Jul 1995 |
| 205.142.72.0/22 | 1k | ARIN | US | 19th Jul 1995 |
| 205.142.8.0/22 | 1k | ARIN | US | 21st Feb 1995 |
| 205.142.80.0/22 | 1k | ARIN | US | 27th Jul 1995 |
| 205.142.84.0/22 | 1k | ARIN | US | 28th Jul 1995 |
| 205.142.96.0/22 | 1k | ARIN | US | 31st Jul 1995 |
| 205.143.104.0/21 | 2k | ARIN | US | 11th May 1995 |
| 205.143.112.0/21 | 2k | ARIN | US | 11th May 1995 |
| 205.143.144.0/21 | 2k | ARIN | US | 16th May 1995 |
| 205.143.16.0/21 | 2k | ARIN | US | 15th Mar 1995 |
| 205.143.160.0/21 | 2k | ARIN | US | 19th May 1995 |
| 205.143.168.0/21 | 2k | ARIN | US | 23rd May 1995 |
| 205.143.176.0/21 | 2k | ARIN | US | 30th May 1995 |
| 205.143.184.0/21 | 2k | ARIN | US | 30th May 1995 |
| 205.143.24.0/21 | 2k | ARIN | US | 17th Mar 1995 |
| 205.143.56.0/21 | 2k | ARIN | US | 27th Mar 1995 |
| 205.143.80.0/21 | 2k | ARIN | US | 5th May 1995 |
| 205.143.88.0/21 | 2k | ARIN | US | 8th May 1995 |
| 205.143.96.0/21 | 2k | ARIN | US | 11th May 1995 |
| 205.144.0.0/20 | 4.1k | ARIN | US | 21st Feb 1995 |
| 205.144.176.0/20 | 4.1k | ARIN | US | 25th Apr 1995 |
| 205.144.192.0/20 | 4.1k | ARIN | US | 18th May 1995 |
| 205.144.240.0/20 | 4.1k | ARIN | US | 30th May 1995 |
| 205.145.152.0/22 | 1k | ARIN | US | 2nd Oct 2008 |
| 205.145.158.0/24 | 256 | ARIN | US | 11th Jan 1995 |
| 205.145.160.0/24 | 256 | ARIN | US | 15th Mar 1995 |
| 205.145.161.0/24 | 256 | ARIN | US | 13th Dec 2013 |
| 205.145.162.0/24 | 256 | ARIN | US | 13th Dec 2013 |