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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
26,277 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 164.55.0.0/17 | 32.8k | ARIN |  US | 9th Dec 1992 |
| 164.55.128.0/18 | 16.4k | ARIN | US | 9th Dec 1992 |
| 164.55.192.0/19 | 8.2k | ARIN | US | 9th Dec 1992 |
| 164.56.0.0/16 | 65.5k | ARIN | US | 5th Dec 1992 |
| 164.57.0.0/17 | 32.8k | ARIN | US | 5th Dec 1992 |
| 164.57.128.0/18 | 16.4k | ARIN | US | 5th Dec 1992 |
| 164.57.224.0/19 | 8.2k | ARIN | US | 5th Dec 1992 |
| 164.68.0.0/18 | 16.4k | ARIN | US | 17th Dec 1992 |
| 164.72.0.0/16 | 65.5k | ARIN | US | 16th Nov 1992 |
| 164.79.0.0/16 | 65.5k | ARIN | US | 29th Dec 1992 |
| 164.84.0.0/16 | 65.5k | ARIN | US | 11th Jan 1993 |
| 164.89.0.0/16 | 65.5k | ARIN | US | 21st Jan 1993 |
| 164.91.0.0/16 | 65.5k | ARIN | US | 25th Jan 1993 |
| 164.93.0.0/17 | 32.8k | ARIN | US | 11th Jul 2023 |
| 165.100.160.0/20 | 4.1k | ARIN | US | 26th Jun 2024 |
| 165.105.0.0/16 | 65.5k | ARIN | US | 12th May 1993 |
| 165.116.0.0/16 | 65.5k | ARIN | US | 20th May 1993 |
| 165.126.0.0/16 | 65.5k | ARIN | US | 1st Jun 1993 |
| 165.135.0.0/16 | 65.5k | ARIN | US | 9th Jun 1993 |
| 165.136.0.0/16 | 65.5k | ARIN | US | 9th Jun 1993 |
| 165.140.0.0/22 | 1k | ARIN | US | 7th Jan 2022 |
| 165.140.104.0/24 | 256 | ARIN | US | 11th Apr 2024 |
| 165.140.136.0/22 | 1k | ARIN | US | 2nd Dec 2021 |
| 165.140.188.0/24 | 256 | ARIN | US | 4th Nov 2021 |
| 165.140.4.0/22 | 1k | ARIN | US | 6th Jan 2022 |
| 165.140.52.0/24 | 256 | ARIN | US | 23rd Dec 2024 |
| 165.140.57.0/24 | 256 | ARIN | US | 2nd Apr 2026 |
| 165.140.80.0/22 | 1k | ARIN | US | 6th Jan 2022 |
| 165.153.0.0/16 | 65.5k | ARIN | US | 17th Jun 1993 |
| 165.157.0.0/16 | 65.5k | ARIN | US | 21st Jun 1993 |
| 165.163.0.0/16 | 65.5k | ARIN | US | 25th Jun 1993 |
| 165.164.0.0/16 | 65.5k | ARIN | US | 28th Jun 1993 |
| 165.167.0.0/16 | 65.5k | ARIN | US | 11th Sept 2018 |
| 165.168.0.0/16 | 65.5k | ARIN | US | 6th Jul 1993 |
| 165.172.0.0/16 | 65.5k | ARIN | US | 8th Jul 1993 |
| 165.174.0.0/16 | 65.5k | ARIN | US | 12th Jul 1993 |
| 165.176.0.0/16 | 65.5k | ARIN | US | 19th Jul 1993 |
| 165.177.0.0/16 | 65.5k | ARIN | US | 19th Jul 1993 |
| 165.179.0.0/16 | 65.5k | ARIN | US | 21st Jul 1993 |
| 165.188.0.0/18 | 16.4k | ARIN | US | 27th Aug 1993 |
| 165.198.0.0/16 | 65.5k | ARIN | US | 16th Aug 1993 |
| 165.2.0.0/18 | 16.4k | ARIN | US | 24th Mar 1993 |
| 165.2.88.0/21 | 2k | ARIN | US | 24th Mar 1993 |
| 165.203.0.0/16 | 65.5k | ARIN | US | 25th Aug 1993 |
| 165.217.144.0/20 | 4.1k | ARIN | US | 7th Sept 1993 |
| 165.238.0.0/16 | 65.5k | ARIN | US | 1st Oct 1993 |
| 165.28.0.0/16 | 65.5k | ARIN | US | 6th Apr 1993 |
| 165.30.0.0/16 | 65.5k | ARIN | US | 8th Apr 1993 |
| 165.32.0.0/13 | 524k | ARIN | US | 11th Feb 1993 |
| 165.40.0.0/15 | 131k | ARIN | US | 11th Feb 1993 |