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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
Browse by country
Countries with the most unannounced blocks, largest first.
Unannounced blocks in United States
26,963 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 156.154.60.0/24 | 256 | 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 |
| 156.9.100.0/22 | 1k | ARIN | US | 8th Oct 2026 |
| 156.9.104.0/22 | 1k | ARIN | US | 2nd Nov 2026 |
| 156.9.108.0/22 | 1k | ARIN | US | 8th Oct 2026 |
| 156.9.120.0/22 | 1k | ARIN | US | 8th Oct 2026 |
| 156.9.132.0/22 | 1k | ARIN | US | 6th Oct 2026 |