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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
27,034 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 199.167.172.0/22 | 1k | ARIN |  US | 8th Jun 2011 |
| 199.167.188.0/23 | 512 | ARIN | US | 17th Dec 2025 |
| 199.167.190.0/24 | 256 | ARIN | US | 17th Dec 2025 |
| 199.167.242.0/24 | 256 | ARIN | US | 16th Jun 2011 |
| 199.168.13.0/24 | 256 | ARIN | US | 31st Mar 2009 |
| 199.168.132.0/22 | 1k | ARIN | US | 8th Oct 2025 |
| 199.168.14.0/24 | 256 | ARIN | US | 31st Mar 2009 |
| 199.168.228.0/22 | 1k | ARIN | US | 8th Feb 2022 |
| 199.168.25.0/24 | 256 | ARIN | US | 24th Jul 2012 |
| 199.168.252.0/22 | 1k | ARIN | US | 28th Jun 2011 |
| 199.168.40.0/24 | 256 | ARIN | US | 15th Feb 1994 |
| 199.175.110.0/23 | 512 | ARIN | US | 16th Feb 1994 |
| 199.175.120.0/22 | 1k | ARIN | US | 16th Feb 1994 |
| 199.175.240.0/24 | 256 | ARIN | US | 7th Dec 2021 |
| 199.180.12.0/23 | 512 | ARIN | US | 18th Feb 1994 |
| 199.180.14.0/24 | 256 | ARIN | US | 18th Feb 1994 |
| 199.180.224.0/21 | 2k | ARIN | US | 13th Jul 2011 |
| 199.180.32.0/20 | 4.1k | ARIN | US | 22nd Feb 1994 |
| 199.180.48.0/22 | 1k | ARIN | US | 22nd Feb 1994 |
| 199.181.0.0/21 | 2k | ARIN | US | 4th Mar 1994 |
| 199.181.100.0/22 | 1k | ARIN | US | 25th Jul 1994 |
| 199.181.104.0/24 | 256 | ARIN | US | 26th Jul 1994 |
| 199.181.105.0/24 | 256 | ARIN | US | 26th Jul 1994 |
| 199.181.106.0/24 | 256 | ARIN | US | 26th Jul 1994 |
| 199.181.109.0/24 | 256 | ARIN | US | 26th Jul 1994 |
| 199.181.110.0/23 | 512 | ARIN | US | 26th Jul 1994 |
| 199.181.112.0/23 | 512 | ARIN | US | 26th Jul 1994 |
| 199.181.114.0/24 | 256 | ARIN | US | 26th Jul 1994 |
| 199.181.115.0/24 | 256 | ARIN | US | 26th Jul 1994 |
| 199.181.116.0/24 | 256 | ARIN | US | 26th Jul 1994 |
| 199.181.117.0/24 | 256 | ARIN | US | 26th Jul 1994 |
| 199.181.118.0/24 | 256 | ARIN | US | 26th Jul 1994 |
| 199.181.119.0/24 | 256 | ARIN | US | 26th Jul 1994 |
| 199.181.120.0/24 | 256 | ARIN | US | 26th Jul 1994 |
| 199.181.121.0/24 | 256 | ARIN | US | 27th Jul 1994 |
| 199.181.124.0/24 | 256 | ARIN | US | 27th Jul 1994 |
| 199.181.125.0/24 | 256 | ARIN | US | 27th Jul 1994 |
| 199.181.126.0/24 | 256 | ARIN | US | 27th Jul 1994 |
| 199.181.128.0/24 | 256 | ARIN | US | 22nd Mar 1994 |
| 199.181.129.0/24 | 256 | ARIN | US | 28th Mar 1994 |
| 199.181.132.0/22 | 1k | ARIN | US | 28th Mar 1994 |
| 199.181.138.0/24 | 256 | ARIN | US | 29th Mar 1994 |
| 199.181.139.0/24 | 256 | ARIN | US | 29th Mar 1994 |
| 199.181.141.0/24 | 256 | ARIN | US | 14th Jul 1994 |
| 199.181.142.0/24 | 256 | ARIN | US | 29th Mar 1994 |
| 199.181.143.0/24 | 256 | ARIN | US | 29th Mar 1994 |
| 199.181.144.0/24 | 256 | ARIN | US | 29th Mar 1994 |
| 199.181.145.0/24 | 256 | ARIN | US | 29th Mar 1994 |
| 199.181.146.0/24 | 256 | ARIN | US | 29th Mar 1994 |
| 199.181.147.0/24 | 256 | ARIN | US | 29th Mar 1994 |