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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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 |
|---|---|---|---|---|
| 155.35.44.0/23 | 512 | ARIN |  US | 4th Feb 1992 |
| 155.35.48.0/20 | 4.1k | ARIN | US | 4th Feb 1992 |
| 155.35.64.0/18 | 16.4k | ARIN | US | 4th Feb 1992 |
| 155.35.8.0/21 | 2k | ARIN | US | 4th Feb 1992 |
| 155.36.0.0/16 | 65.5k | ARIN | US | 8th Apr 1992 |
| 155.46.64.0/19 | 8.2k | ARIN | US | 26th Aug 1994 |
| 155.46.96.0/19 | 8.2k | ARIN | US | 26th Aug 1994 |
| 155.51.0.0/16 | 65.5k | ARIN | US | 23rd Mar 1992 |
| 155.61.0.0/16 | 65.5k | ARIN | US | 30th Oct 1991 |
| 155.67.0.0/16 | 65.5k | ARIN | US | 31st Oct 1991 |
| 155.68.0.0/16 | 65.5k | ARIN | US | 30th Oct 1991 |
| 155.90.0.0/16 | 65.5k | ARIN | US | 31st Oct 1991 |
| 155.94.234.0/24 | 256 | ARIN | US | 11th Jun 2014 |
| 155.94.80.0/20 | 4.1k | ARIN | US | 13th Oct 2022 |
| 155.96.0.0/16 | 65.5k | ARIN | US | 13th Nov 1991 |
| 156.100.0.0/16 | 65.5k | ARIN | US | 24th Dec 1991 |
| 156.102.0.0/16 | 65.5k | ARIN | US | 24th Dec 1991 |
| 156.103.0.0/16 | 65.5k | ARIN | US | 24th Dec 1991 |
| 156.104.0.0/16 | 65.5k | ARIN | US | 24th Dec 1991 |
| 156.105.0.0/16 | 65.5k | ARIN | US | 24th Dec 1991 |
| 156.117.0.0/16 | 65.5k | ARIN | US | 8th Jan 1992 |
| 156.119.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.120.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.121.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.122.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.123.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.124.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.125.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.126.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.127.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.128.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.129.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.130.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.131.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.132.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.136.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.140.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.141.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.152.0.0/16 | 65.5k | ARIN | US | 17th Dec 1993 |
| 156.154.114.0/23 | 512 | ARIN | US | 18th Dec 2003 |
| 156.154.134.0/24 | 256 | ARIN | US | 18th Dec 2003 |
| 156.154.146.0/24 | 256 | ARIN | US | 18th Dec 2003 |
| 156.154.147.0/24 | 256 | ARIN | US | 18th Dec 2003 |
| 156.154.168.0/24 | 256 | ARIN | US | 18th Dec 2003 |
| 156.154.176.0/23 | 512 | ARIN | US | 18th Dec 2003 |
| 156.154.185.0/24 | 256 | ARIN | US | 18th Dec 2003 |
| 156.154.186.0/23 | 512 | ARIN | US | 18th Dec 2003 |
| 156.154.204.0/22 | 1k | ARIN | US | 18th Dec 2003 |
| 156.154.32.0/23 | 512 | ARIN | US | 18th Dec 2003 |
| 156.154.44.0/22 | 1k | ARIN | US | 18th Dec 2003 |