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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
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Countries with the most unannounced blocks, largest first.
Unannounced blocks in United States
26,951 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 206.251.128.0/19 | 8.2k | ARIN |  US | 25th Jan 1996 |
| 206.251.56.0/22 | 1k | ARIN | US | 6th Oct 2025 |
| 206.251.96.0/19 | 8.2k | ARIN | US | 23rd Jan 1996 |
| 206.252.0.0/19 | 8.2k | ARIN | US | 12th Dec 2000 |
| 206.253.96.0/19 | 8.2k | ARIN | US | 24th Jun 1996 |
| 206.28.184.0/21 | 2k | ARIN | US | 24th May 1995 |
| 206.29.0.0/17 | 32.8k | ARIN | US | 24th May 1995 |
| 206.29.144.0/20 | 4.1k | ARIN | US | 24th May 1995 |
| 206.29.192.0/18 | 16.4k | ARIN | US | 24th May 1995 |
| 206.40.0.0/19 | 8.2k | ARIN | US | 30th May 1995 |
| 206.40.64.0/19 | 8.2k | ARIN | US | 2nd Jun 1995 |
| 206.41.100.0/22 | 1k | ARIN | US | 1st Oct 2026 |
| 206.41.105.0/24 | 256 | ARIN | US | 20th May 2014 |
| 206.41.108.0/24 | 256 | ARIN | US | 17th Sept 2014 |
| 206.41.109.0/24 | 256 | ARIN | US | 18th Sept 2014 |
| 206.41.110.0/24 | 256 | ARIN | US | 17th Oct 2014 |
| 206.41.128.0/20 | 4.1k | ARIN | US | 16th Jun 1995 |
| 206.41.160.0/19 | 8.2k | ARIN | US | 16th Jun 1995 |
| 206.41.96.0/22 | 1k | ARIN | US | 13th Oct 2026 |
| 206.51.1.0/24 | 256 | ARIN | US | 20th May 1997 |
| 206.51.30.0/24 | 256 | ARIN | US | 6th Sept 2007 |
| 206.51.36.0/22 | 1k | ARIN | US | 8th Jun 2007 |
| 206.51.40.0/21 | 2k | ARIN | US | 30th Jul 2007 |
| 206.51.7.0/24 | 256 | ARIN | US | 6th Jul 2007 |
| 206.53.128.0/21 | 2k | ARIN | US | 21st Jun 1995 |
| 206.53.137.0/24 | 256 | ARIN | US | 8th Jan 2015 |
| 206.53.139.0/24 | 256 | ARIN | US | 26th Feb 2015 |
| 206.53.143.0/24 | 256 | ARIN | US | 15th Apr 2015 |
| 206.53.168.0/22 | 1k | ARIN | US | 19th Oct 2015 |
| 206.53.172.0/23 | 512 | ARIN | US | 19th Oct 2015 |
| 206.53.174.0/24 | 256 | ARIN | US | 19th Oct 2015 |
| 206.53.175.0/24 | 256 | ARIN | US | 4th Nov 2015 |
| 206.53.200.0/24 | 256 | ARIN | US | 2nd Dec 2015 |
| 206.53.201.0/24 | 256 | ARIN | US | 22nd Feb 2016 |
| 206.53.202.0/24 | 256 | ARIN | US | 14th Mar 2016 |
| 206.53.203.0/24 | 256 | ARIN | US | 11th Apr 2016 |
| 206.53.204.0/24 | 256 | ARIN | US | 3rd Jun 2016 |
| 206.53.205.0/24 | 256 | ARIN | US | 22nd Aug 2016 |
| 206.53.206.0/24 | 256 | ARIN | US | 8th Sept 2016 |
| 206.53.207.0/24 | 256 | ARIN | US | 15th Nov 2016 |
| 206.53.32.0/21 | 2k | ARIN | US | 20th Jun 1995 |
| 206.53.40.0/21 | 2k | ARIN | US | 14th Nov 2008 |
| 206.54.224.0/19 | 8.2k | ARIN | US | 24th Jul 1995 |
| 206.55.160.0/22 | 1k | ARIN | US | 25th Jul 1995 |
| 206.55.164.0/22 | 1k | ARIN | US | 2nd Jul 2025 |
| 206.55.168.0/22 | 1k | ARIN | US | 17th Nov 2008 |
| 206.55.192.0/22 | 1k | ARIN | US | 1st Oct 2026 |
| 206.55.196.0/22 | 1k | ARIN | US | 13th Nov 2013 |
| 206.55.200.0/21 | 2k | ARIN | US | 18th Nov 2008 |
| 206.55.221.0/24 | 256 | ARIN | US | 17th Feb 2023 |