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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
26,302 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 204.152.138.0/23 | 512 | ARIN |  US | 8th Mar 1995 |
| 204.152.142.0/23 | 512 | ARIN | US | 10th Mar 1995 |
| 204.152.144.0/23 | 512 | ARIN | US | 17th Mar 1995 |
| 204.152.146.0/23 | 512 | ARIN | US | 10th Feb 2011 |
| 204.152.16.0/23 | 512 | ARIN | US | 17th Oct 1994 |
| 204.152.160.0/22 | 1k | ARIN | US | 13th Feb 1996 |
| 204.152.166.0/23 | 512 | ARIN | US | 22nd Jun 1996 |
| 204.152.168.0/21 | 2k | ARIN | US | 8th Aug 1996 |
| 204.152.178.0/23 | 512 | ARIN | US | 27th Aug 1996 |
| 204.152.18.0/23 | 512 | ARIN | US | 31st Jan 2011 |
| 204.152.26.0/23 | 512 | ARIN | US | 31st Oct 1994 |
| 204.152.28.0/23 | 512 | ARIN | US | 31st Oct 1994 |
| 204.152.30.0/23 | 512 | ARIN | US | 1st Nov 1994 |
| 204.152.36.0/23 | 512 | ARIN | US | 10th Nov 1994 |
| 204.152.4.0/23 | 512 | ARIN | US | 17th Sept 1994 |
| 204.152.52.0/23 | 512 | ARIN | US | 2nd Dec 1994 |
| 204.152.54.0/23 | 512 | ARIN | US | 8th Dec 1994 |
| 204.152.56.0/23 | 512 | ARIN | US | 8th Dec 1994 |
| 204.152.58.0/23 | 512 | ARIN | US | 8th Dec 1994 |
| 204.152.6.0/23 | 512 | ARIN | US | 27th Jan 2011 |
| 204.152.70.0/23 | 512 | ARIN | US | 22nd Dec 1994 |
| 204.152.72.0/23 | 512 | ARIN | US | 23rd Dec 1994 |
| 204.152.74.0/23 | 512 | ARIN | US | 3rd Jan 1995 |
| 204.152.76.0/23 | 512 | ARIN | US | 7th Jan 1995 |
| 204.152.84.0/22 | 1k | ARIN | US | 20th Jan 1995 |
| 204.152.88.0/23 | 512 | ARIN | US | 20th Jan 1995 |
| 204.153.108.0/22 | 1k | ARIN | US | 9th Nov 1994 |
| 204.153.112.0/22 | 1k | ARIN | US | 10th Nov 1994 |
| 204.153.116.0/22 | 1k | ARIN | US | 16th Nov 1994 |
| 204.153.124.0/22 | 1k | ARIN | US | 29th Nov 1994 |
| 204.153.132.0/23 | 512 | ARIN | US | 30th Nov 1994 |
| 204.153.134.0/24 | 256 | ARIN | US | 30th Nov 1994 |
| 204.153.136.0/23 | 512 | ARIN | US | 30th Nov 1994 |
| 204.153.138.0/24 | 256 | ARIN | US | 30th Nov 1994 |
| 204.153.164.0/22 | 1k | ARIN | US | 19th Dec 1994 |
| 204.153.168.0/22 | 1k | ARIN | US | 19th Dec 1994 |
| 204.153.172.0/22 | 1k | ARIN | US | 3rd Jan 1995 |
| 204.153.180.0/22 | 1k | ARIN | US | 5th Jan 1995 |
| 204.153.188.0/22 | 1k | ARIN | US | 7th Jan 1995 |
| 204.153.196.0/22 | 1k | ARIN | US | 13th Jan 1995 |
| 204.153.20.0/22 | 1k | ARIN | US | 4th Oct 1994 |
| 204.153.200.0/22 | 1k | ARIN | US | 17th Jan 1995 |
| 204.153.204.0/23 | 512 | ARIN | US | 17th Jan 1995 |
| 204.153.208.0/22 | 1k | ARIN | US | 17th Jan 1995 |
| 204.153.216.0/23 | 512 | ARIN | US | 20th Jan 1995 |
| 204.153.218.0/24 | 256 | ARIN | US | 20th Jan 1995 |
| 204.153.220.0/22 | 1k | ARIN | US | 1st Oct 2021 |
| 204.153.232.0/22 | 1k | ARIN | US | 10th Feb 1995 |
| 204.153.236.0/22 | 1k | ARIN | US | 10th Feb 1995 |
| 204.153.248.0/21 | 2k | ARIN | US | 15th Feb 1995 |