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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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 registered through ARIN
30,434 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 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 |
| 165.250.0.0/16 | 65.5k | ARIN |  JE | 13th 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 |
| 165.44.0.0/14 | 262k | ARIN | US | 11th Feb 1993 |
| 165.48.0.0/16 | 65.5k | ARIN | US | 11th Feb 1993 |
| 165.64.0.0/16 | 65.5k | ARIN | US | 9th Apr 1993 |
| 165.7.0.0/16 | 65.5k | ARIN | US | 26th Mar 1993 |
| 165.71.0.0/16 | 65.5k | ARIN | US | 15th Apr 1993 |
| 165.77.0.0/16 | 65.5k | ARIN | US | 22nd Apr 1993 |
| 165.80.0.0/16 | 65.5k | ARIN | US | 26th Apr 1993 |
| 166.101.0.0/16 | 65.5k | ARIN | US | 30th Nov 1993 |
| 166.105.0.0/16 | 65.5k | ARIN | US | 3rd Dec 1993 |
| 166.108.32.0/19 | 8.2k | ARIN | US | 6th Dec 1993 |
| 166.112.0.0/16 | 65.5k | ARIN | US | 10th Dec 1993 |
| 166.113.128.0/17 | 32.8k | ARIN | US | 19th May 2021 |
| 166.115.0.0/16 | 65.5k | ARIN | US | 14th Dec 1993 |
| 166.116.0.0/16 | 65.5k | ARIN | US | 14th Dec 1993 |
| 166.124.0.0/16 | 65.5k | ARIN | US | 3rd Jan 1994 |
| 166.126.0.0/16 | 65.5k | ARIN | US | 5th Jan 1994 |
| 166.16.0.0/16 | 65.5k | ARIN | US | 21st Jun 1993 |
| 166.17.0.0/16 | 65.5k | ARIN | US | 21st Jun 1993 |
| 166.178.0.0/16 | 65.5k | ARIN | US | 1st Apr 2025 |
| 166.179.0.0/18 | 16.4k | ARIN | US | 1st Apr 2025 |
| 166.179.104.0/22 | 1k | ARIN | US | 1st Apr 2025 |
| 166.179.108.0/22 | 1k | ARIN | US | 25th Mar 2025 |
| 166.179.112.0/20 | 4.1k | ARIN | US | 25th Mar 2025 |
| 166.179.128.0/17 | 32.8k | ARIN | US | 25th Mar 2025 |
| 166.179.96.0/21 | 2k | ARIN | US | 1st Apr 2025 |
| 166.18.0.0/16 | 65.5k | ARIN | US | 21st Jun 1993 |
| 166.221.0.0/16 | 65.5k | ARIN | US | 7th Apr 2025 |
| 166.222.0.0/15 | 131k | ARIN | US | 7th Apr 2025 |
| 166.228.0.0/15 | 131k | ARIN | US | 7th Apr 2025 |
| 166.231.0.0/16 | 65.5k | ARIN | US | 7th Apr 2025 |
| 166.232.0.0/14 | 262k | ARIN | US | 7th Apr 2025 |
| 166.237.0.0/16 | 65.5k | ARIN | US | 25th Mar 2025 |