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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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.
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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 |
|---|---|---|---|---|
| 205.145.164.0/22 | 1k | ARIN |  US | 13th Dec 2013 |
| 205.145.168.0/24 | 256 | ARIN | US | 13th Dec 2013 |
| 205.145.169.0/24 | 256 | ARIN | US | 13th Dec 2013 |
| 205.145.170.0/24 | 256 | ARIN | US | 13th Dec 2013 |
| 205.145.171.0/24 | 256 | ARIN | US | 27th Mar 2014 |
| 205.145.172.0/23 | 512 | ARIN | US | 13th Dec 2013 |
| 205.145.174.0/24 | 256 | ARIN | US | 13th Dec 2013 |
| 205.145.175.0/24 | 256 | ARIN | US | 13th Dec 2013 |
| 205.145.181.0/24 | 256 | ARIN | US | 13th Dec 2013 |
| 205.145.183.0/24 | 256 | ARIN | US | 13th Dec 2013 |
| 205.145.191.0/24 | 256 | ARIN | US | 2nd Apr 2014 |
| 205.147.112.0/20 | 4.1k | ARIN | US | 25th Feb 2008 |
| 205.147.224.0/21 | 2k | ARIN | US | 1st May 2025 |
| 205.148.128.0/18 | 16.4k | ARIN | US | 5th Apr 1995 |
| 205.148.64.0/18 | 16.4k | ARIN | US | 31st Mar 1995 |
| 205.149.192.0/18 | 16.4k | ARIN | US | 11th Apr 1995 |
| 205.149.96.0/19 | 8.2k | ARIN | US | 17th Mar 1995 |
| 205.151.189.0/24 | 256 | ARIN | US | 13th Apr 2012 |
| 205.153.0.0/22 | 1k | ARIN | US | 21st Mar 1995 |
| 205.153.12.0/22 | 1k | ARIN | US | 22nd Mar 1995 |
| 205.153.124.0/22 | 1k | ARIN | US | 26th May 1995 |
| 205.153.132.0/22 | 1k | ARIN | US | 30th May 1995 |
| 205.153.136.0/22 | 1k | ARIN | US | 31st May 1995 |
| 205.153.148.0/22 | 1k | ARIN | US | 31st May 1995 |
| 205.153.160.0/22 | 1k | ARIN | US | 5th Jun 1995 |
| 205.153.164.0/22 | 1k | ARIN | US | 5th Jun 1995 |
| 205.153.172.0/22 | 1k | ARIN | US | 8th Jun 1995 |
| 205.153.184.0/22 | 1k | ARIN | US | 13th Jun 1995 |
| 205.153.188.0/22 | 1k | ARIN | US | 14th Jun 1995 |
| 205.153.192.0/22 | 1k | ARIN | US | 15th Jun 1995 |
| 205.153.196.0/22 | 1k | ARIN | US | 27th Oct 1997 |
| 205.153.20.0/22 | 1k | ARIN | US | 22nd Mar 1995 |
| 205.153.200.0/22 | 1k | ARIN | US | 15th Jun 1995 |
| 205.153.212.0/22 | 1k | ARIN | US | 19th Jun 1995 |
| 205.153.216.0/22 | 1k | ARIN | US | 27th Jun 1995 |
| 205.153.231.0/24 | 256 | ARIN | US | 29th Jun 1995 |
| 205.153.236.0/22 | 1k | ARIN | US | 6th Jul 1995 |
| 205.153.24.0/22 | 1k | ARIN | US | 24th Mar 1995 |
| 205.153.244.0/22 | 1k | ARIN | US | 12th Jul 1995 |
| 205.153.248.0/22 | 1k | ARIN | US | 12th Jul 1995 |
| 205.153.4.0/22 | 1k | ARIN | US | 21st Mar 1995 |
| 205.153.40.0/22 | 1k | ARIN | US | 6th Apr 1995 |
| 205.153.56.0/22 | 1k | ARIN | US | 25th Apr 1995 |
| 205.153.64.0/22 | 1k | ARIN | US | 1st May 1995 |
| 205.153.68.0/22 | 1k | ARIN | US | 1st May 1995 |
| 205.153.72.0/22 | 1k | ARIN | US | 2nd May 1995 |
| 205.153.76.0/22 | 1k | ARIN | US | 5th May 1995 |
| 205.156.192.0/18 | 16.4k | ARIN | US | 17th Mar 1995 |
| 205.159.0.0/24 | 256 | ARIN | US | 9th Mar 1995 |
| 205.159.10.0/24 | 256 | ARIN | US | 10th Mar 1995 |