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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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 |
|---|---|---|---|---|
| 161.103.0.0/16 | 65.5k | ARIN |  US | 23rd Jun 1992 |
| 161.104.112.0/20 | 4.1k | RIPE NCC | US | 24th Jun 1992 |
| 161.104.128.0/19 | 8.2k | RIPE NCC | US | 24th Jun 1992 |
| 161.104.184.0/21 | 2k | RIPE NCC |  IE | 24th Jun 1992 |
| 161.104.28.0/22 | 1k | RIPE NCC |  RU | 24th Jun 1992 |
| 161.104.76.0/23 | 512 | RIPE NCC |  NL | 24th Jun 1992 |
| 161.104.78.0/23 | 512 | RIPE NCC |  CR | 24th Jun 1992 |
| 161.104.92.0/23 | 512 | RIPE NCC | RU | 24th Jun 1992 |
| 161.104.94.0/23 | 512 | RIPE NCC | RU | 24th Jun 1992 |
| 161.108.0.0/18 | 16.4k | ARIN | US | 25th Jun 1992 |
| 161.108.112.0/21 | 2k | ARIN | US | 25th Jun 1992 |
| 161.108.121.0/24 | 256 | ARIN | US | 25th Jun 1992 |
| 161.108.124.0/22 | 1k | ARIN | US | 25th Jun 1992 |
| 161.108.131.0/24 | 256 | ARIN | US | 16th Oct 2025 |
| 161.108.132.0/22 | 1k | ARIN | US | 25th Jun 1992 |
| 161.108.144.0/20 | 4.1k | ARIN | US | 25th Jun 1992 |
| 161.108.160.0/22 | 1k | ARIN | US | 25th Jun 1992 |
| 161.108.164.0/23 | 512 | ARIN | US | 25th Jun 1992 |
| 161.108.167.0/24 | 256 | ARIN | US | 25th Jun 1992 |
| 161.108.192.0/21 | 2k | ARIN | US | 21st Jul 2025 |
| 161.108.200.0/22 | 1k | ARIN | US | 25th Jun 1992 |
| 161.108.205.0/24 | 256 | ARIN | US | 25th Jun 1992 |
| 161.108.206.0/23 | 512 | ARIN | US | 25th Jun 1992 |
| 161.108.208.0/24 | 256 | ARIN | US | 25th Jun 1992 |
| 161.108.209.0/24 | 256 | RIPE NCC | US | 25th Jun 1992 |
| 161.108.212.0/22 | 1k | ARIN | US | 25th Jun 1992 |
| 161.108.216.0/21 | 2k | ARIN | US | 25th Jun 1992 |
| 161.108.64.0/19 | 8.2k | ARIN | US | 25th Jun 1992 |
| 161.108.96.0/20 | 4.1k | ARIN | US | 25th Jun 1992 |
| 161.121.0.0/17 | 32.8k | ARIN | US | 14th Jul 1992 |
| 161.127.0.0/16 | 65.5k | ARIN | US | 23rd Jul 1992 |
| 161.128.0.0/16 | 65.5k | ARIN | US | 27th Jul 1992 |
| 161.129.177.0/24 | 256 | ARIN | US | 6th Aug 2018 |
| 161.129.189.0/24 | 256 | ARIN | US | 11th Apr 2018 |
| 161.129.191.0/24 | 256 | ARIN | US | 16th Apr 2018 |
| 161.129.246.0/23 | 512 | ARIN | US | 1st Aug 2018 |
| 161.129.30.0/24 | 256 | ARIN |  CA | 29th Mar 2018 |
| 161.129.63.0/24 | 256 | ARIN | US | 30th Mar 2018 |
| 161.129.96.0/19 | 8.2k | ARIN | CA | 29th Mar 2018 |
| 161.13.128.0/19 | 8.2k | ARIN | US | 3rd Mar 2026 |
| 161.144.0.0/16 | 65.5k | ARIN | US | 16th Oct 1992 |
| 161.145.104.0/21 | 2k | ARIN | US | 22nd Oct 1992 |
| 161.145.112.0/20 | 4.1k | ARIN | US | 22nd Oct 1992 |
| 161.145.64.0/19 | 8.2k | ARIN | US | 22nd Oct 1992 |
| 161.147.0.0/16 | 65.5k | RIPE NCC |  IT | 1st Sept 1993 |
| 161.158.0.0/16 | 65.5k | RIPE NCC | NL | 1st Sept 1993 |
| 161.161.0.0/16 | 65.5k | ARIN | US | 31st Dec 1992 |
| 161.182.0.0/16 | 65.5k | ARIN | US | 13th Jan 1993 |
| 161.183.0.0/16 | 65.5k | ARIN | US | 13th Jan 1993 |
| 161.186.0.0/16 | 65.5k | ARIN | US | 15th Jan 1993 |