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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
26,993 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 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 |
| 166.52.0.0/15 | 131k | ARIN | US | 24th Mar 1993 |
| 166.54.0.0/16 | 65.5k | ARIN | US | 24th Mar 1993 |
| 166.55.0.0/16 | 65.5k | ARIN | US | 24th Mar 1993 |
| 166.57.0.0/16 | 65.5k | ARIN | US | 24th Mar 1993 |
| 166.59.0.0/16 | 65.5k | ARIN | US | 24th Mar 1993 |
| 166.60.0.0/16 | 65.5k | ARIN | US | 24th Mar 1993 |
| 166.63.0.0/17 | 32.8k | ARIN | US | 28th Mar 2012 |
| 166.68.0.0/16 | 65.5k | ARIN | US | 25th Oct 1993 |
| 166.71.0.0/16 | 65.5k | ARIN | US | 28th Oct 1993 |
| 166.76.0.0/16 | 65.5k | ARIN | US | 3rd Nov 1993 |
| 166.8.0.0/16 | 65.5k | RIPE NCC | US | 1st Sept 1993 |
| 166.9.0.0/16 | 65.5k | RIPE NCC | US | 1st Sept 1993 |
| 166.97.0.0/16 | 65.5k | ARIN | US | 23rd Jan 1995 |
| 167.101.0.0/16 | 65.5k | ARIN | US | 25th May 1993 |
| 167.104.124.0/22 | 1k | ARIN | US | 28th May 1993 |
| 167.104.49.0/24 | 256 | ARIN | US | 19th Mar 2026 |
| 167.109.0.0/16 | 65.5k | ARIN | US | 7th Jun 1993 |
| 167.117.0.0/16 | 65.5k | ARIN | US | 21st Jun 1993 |
| 167.120.0.0/16 | 65.5k | ARIN | US | 23rd Jun 1993 |
| 167.124.0.0/18 | 16.4k | ARIN | US | 30th Jun 1993 |
| 167.124.64.0/19 | 8.2k | ARIN | US | 30th Jun 1993 |
| 167.125.0.0/16 | 65.5k | ARIN | US | 30th Jun 1993 |
| 167.13.0.0/16 | 65.5k | ARIN | US | 14th Apr 1993 |
| 167.143.0.0/16 | 65.5k | ARIN | US | 19th Jul 1993 |
| 167.145.0.0/16 | 65.5k | ARIN | US | 20th Jul 1993 |
| 167.150.1.0/24 | 256 | ARIN | US | 2nd Aug 1993 |
| 167.150.10.0/23 | 512 | ARIN | US | 8th Aug 2025 |
| 167.150.102.0/24 | 256 | ARIN | US | 2nd Aug 1993 |