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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
85,001 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 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 |
| 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 |
| 156.22.128.0/18 | 16.4k | APNIC |  AU | 1st Nov 1991 |
| 156.22.192.0/19 | 8.2k | APNIC | AU | 1st Nov 1991 |
| 156.22.224.0/20 | 4.1k | APNIC | AU | 1st Nov 1991 |
| 156.24.0.0/16 | 65.5k | ARIN | US | 25th Nov 1991 |
| 156.31.0.0/16 | 65.5k | APNIC |  BN | 3rd Dec 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 |
| 156.67.6.0/29 | 8 | RIPE NCC |  DE | 27th Mar 1992 |
| 156.67.6.128/25 | 128 | RIPE NCC | DE | 27th Mar 1992 |
| 156.67.6.16/29 | 8 | RIPE NCC | DE | 27th Mar 1992 |
| 156.67.6.24/29 | 8 | RIPE NCC | DE | 27th Mar 1992 |
| 156.67.6.32/29 | 8 | RIPE NCC | DE | 27th Mar 1992 |
| 156.67.6.40/29 | 8 | RIPE NCC | DE | 27th Mar 1992 |
| 156.67.6.48/28 | 16 | RIPE NCC | DE | 27th Mar 1992 |
| 156.67.6.64/26 | 64 | RIPE NCC | DE | 27th Mar 1992 |
| 156.67.6.8/29 | 8 | RIPE NCC | DE | 27th Mar 1992 |
| 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 |