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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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 unannounced space registered through ARIN, largest first.
Unannounced blocks in United States
26,277 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 156.154.48.0/22 | 1k | ARIN |  US | 18th Dec 2003 |
| 156.154.61.0/24 | 256 | ARIN | US | 18th Dec 2003 |
| 156.154.81.0/24 | 256 | ARIN | US | 18th Dec 2003 |
| 156.154.93.0/24 | 256 | ARIN | US | 18th Dec 2003 |
| 156.24.0.0/16 | 65.5k | ARIN | US | 25th Nov 1991 |
| 156.32.0.0/16 | 65.5k | ARIN | US | 3rd Dec 1991 |
| 156.36.0.0/16 | 65.5k | ARIN | US | 9th Dec 1991 |
| 156.4.0.0/15 | 131k | ARIN | US | 27th Apr 2020 |
| 156.45.192.0/19 | 8.2k | ARIN | US | 9th Dec 1991 |
| 156.45.240.0/20 | 4.1k | ARIN | US | 9th Dec 1991 |
| 156.70.0.0/23 | 512 | ARIN | US | 19th Dec 1991 |
| 156.70.100.0/22 | 1k | ARIN | US | 19th Dec 1991 |
| 156.70.104.0/22 | 1k | ARIN | US | 19th Dec 1991 |
| 156.70.112.0/22 | 1k | ARIN | US | 22nd Jan 2020 |
| 156.70.118.0/23 | 512 | ARIN | US | 19th Dec 1991 |
| 156.70.122.0/23 | 512 | ARIN | US | 19th Dec 1991 |
| 156.70.14.0/23 | 512 | ARIN | US | 19th Dec 1991 |
| 156.70.148.0/23 | 512 | ARIN | US | 19th Dec 1991 |
| 156.70.152.0/21 | 2k | ARIN | US | 19th Dec 1991 |
| 156.70.160.0/22 | 1k | ARIN | US | 19th Dec 1991 |
| 156.70.168.0/22 | 1k | ARIN | US | 19th Dec 1991 |
| 156.70.18.0/23 | 512 | ARIN | US | 19th Dec 1991 |
| 156.70.180.0/22 | 1k | ARIN | US | 19th Dec 1991 |
| 156.70.192.0/22 | 1k | ARIN | US | 19th Dec 1991 |
| 156.70.20.0/23 | 512 | ARIN | US | 19th Dec 1991 |
| 156.70.216.0/21 | 2k | ARIN | US | 19th Dec 1991 |
| 156.70.224.0/20 | 4.1k | ARIN | US | 22nd Jan 2020 |
| 156.70.240.0/22 | 1k | ARIN | US | 19th Dec 1991 |
| 156.70.248.0/21 | 2k | ARIN | US | 19th Dec 1991 |
| 156.70.26.0/23 | 512 | ARIN | US | 19th Dec 1991 |
| 156.70.28.0/22 | 1k | ARIN | US | 19th Dec 1991 |
| 156.70.32.0/23 | 512 | ARIN | US | 19th Dec 1991 |
| 156.70.36.0/22 | 1k | ARIN | US | 19th Dec 1991 |
| 156.70.40.0/22 | 1k | ARIN | US | 19th Dec 1991 |
| 156.70.44.0/23 | 512 | ARIN | US | 19th Dec 1991 |
| 156.70.54.0/23 | 512 | ARIN | US | 19th Dec 1991 |
| 156.70.56.0/22 | 1k | ARIN | US | 19th Dec 1991 |
| 156.70.6.0/23 | 512 | ARIN | US | 19th Dec 1991 |
| 156.70.74.0/23 | 512 | ARIN | US | 19th Dec 1991 |
| 156.70.78.0/23 | 512 | ARIN | US | 19th Dec 1991 |
| 156.70.90.0/23 | 512 | ARIN | US | 19th Dec 1991 |
| 156.70.92.0/22 | 1k | ARIN | US | 19th Dec 1991 |
| 156.79.0.0/16 | 65.5k | ARIN | US | 19th Dec 1991 |
| 156.81.0.0/16 | 65.5k | ARIN | US | 19th Dec 1991 |
| 156.82.0.0/16 | 65.5k | ARIN | US | 19th Dec 1991 |
| 157.121.0.0/16 | 65.5k | ARIN | US | 19th Dec 1991 |
| 157.126.0.0/16 | 65.5k | ARIN | US | 2nd Jan 1992 |
| 157.14.192.0/20 | 4.1k | ARIN | US | 26th Jun 2024 |
| 157.14.224.0/20 | 4.1k | ARIN | US | 26th Jun 2024 |
| 157.14.240.0/21 | 2k | ARIN | US | 26th Jun 2024 |