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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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 |
|---|---|---|---|---|
| 199.33.252.0/24 | 256 | ARIN |  US | 22nd Jan 1994 |
| 199.33.254.0/24 | 256 | ARIN | US | 22nd Jan 1994 |
| 199.33.255.0/24 | 256 | ARIN | US | 27th Oct 2015 |
| 199.33.66.0/23 | 512 | ARIN | US | 9th Jul 2015 |
| 199.33.81.0/24 | 256 | ARIN | US | 3rd Dec 1999 |
| 199.34.109.0/24 | 256 | ARIN | US | 23rd Sept 1996 |
| 199.34.124.0/24 | 256 | ARIN | US | 27th Oct 2008 |
| 199.34.128.0/18 | 16.4k | ARIN | US | 7th Jan 1994 |
| 199.34.192.0/19 | 8.2k | ARIN | US | 7th Jan 1994 |
| 199.34.224.0/22 | 1k | ARIN | US | 7th Jan 1994 |
| 199.34.243.0/24 | 256 | ARIN | US | 9th Jan 2023 |
| 199.35.0.0/19 | 8.2k | ARIN | US | 22nd Oct 1993 |
| 199.35.128.0/17 | 32.8k | ARIN | US | 22nd Oct 1993 |
| 199.35.32.0/20 | 4.1k | ARIN | US | 22nd Oct 1993 |
| 199.35.96.0/19 | 8.2k | ARIN | US | 22nd Oct 1993 |
| 199.36.112.0/22 | 1k | ARIN | US | 2nd Nov 2011 |
| 199.36.144.0/21 | 2k | ARIN | US | 21st Sept 2010 |
| 199.36.164.0/22 | 1k | ARIN | US | 23rd Sept 2010 |
| 199.36.168.0/22 | 1k | ARIN | US | 24th Sept 2010 |
| 199.36.24.0/24 | 256 | ARIN | US | 25th Oct 1993 |
| 199.36.25.0/24 | 256 | ARIN | US | 27th Dec 2024 |
| 199.36.8.0/23 | 512 | ARIN | US | 27th Oct 1993 |
| 199.38.0.0/21 | 2k | ARIN | US | 4th Nov 1993 |
| 199.38.128.0/24 | 256 | ARIN | US | 8th Nov 1993 |
| 199.38.129.0/24 | 256 | ARIN | US | 8th Nov 1993 |
| 199.38.130.0/24 | 256 | ARIN | US | 8th Nov 1993 |
| 199.38.131.0/24 | 256 | ARIN | US | 8th Nov 1993 |
| 199.38.134.0/23 | 512 | ARIN | US | 8th Nov 1993 |
| 199.38.136.0/24 | 256 | ARIN | US | 8th Nov 1993 |
| 199.38.137.0/24 | 256 | ARIN | US | 9th Nov 1993 |
| 199.38.138.0/24 | 256 | ARIN | US | 9th Nov 1993 |
| 199.38.139.0/24 | 256 | ARIN | US | 9th Nov 1993 |
| 199.38.140.0/24 | 256 | ARIN | US | 10th Nov 1993 |
| 199.38.141.0/24 | 256 | ARIN | US | 10th Nov 1993 |
| 199.38.142.0/24 | 256 | ARIN | US | 10th Nov 1993 |
| 199.38.143.0/24 | 256 | ARIN | US | 27th Aug 2015 |
| 199.38.144.0/24 | 256 | ARIN | US | 10th Nov 1993 |
| 199.38.145.0/24 | 256 | ARIN | US | 10th Nov 1993 |
| 199.38.146.0/24 | 256 | ARIN | US | 10th Nov 1993 |
| 199.38.156.0/24 | 256 | ARIN | US | 12th Nov 1993 |
| 199.38.157.0/24 | 256 | ARIN | US | 12th Nov 1993 |
| 199.38.16.0/21 | 2k | ARIN | US | 28th Oct 1993 |
| 199.38.176.0/22 | 1k | ARIN | US | 14th Nov 2011 |
| 199.38.224.0/21 | 2k | ARIN | US | 3rd Sept 2024 |
| 199.38.24.0/24 | 256 | ARIN | US | 28th Oct 1993 |
| 199.38.251.0/24 | 256 | ARIN | US | 3rd Oct 2025 |
| 199.38.8.0/21 | 2k | ARIN | US | 1st Nov 1993 |
| 199.38.88.0/21 | 2k | ARIN | US | 7th Nov 2011 |
| 199.39.0.0/16 | 65.5k | ARIN | US | 28th Oct 1993 |
| 199.4.0.0/21 | 2k | ARIN | US | 14th Sept 1993 |