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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
84,584 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 51.166.0.0/15 | 131k | RIPE NCC |  US | 1st Sept 1993 |
| 51.18.0.0/16 | 65.5k | RIPE NCC |  DE | 1st Sept 1993 |
| 51.2.0.0/16 | 65.5k | RIPE NCC |  GB | 1st Sept 1993 |
| 51.204.0.0/15 | 131k | RIPE NCC | US | 1st Sept 1993 |
| 51.206.0.0/15 | 131k | RIPE NCC | US | 1st Sept 1993 |
| 51.226.0.0/15 | 131k | RIPE NCC | US | 1st Sept 1993 |
| 51.234.0.0/16 | 65.5k | RIPE NCC | GB | 1st Sept 1993 |
| 51.238.0.0/15 | 131k | RIPE NCC | GB | 1st Sept 1993 |
| 51.242.0.0/15 | 131k | RIPE NCC | GB | 1st Sept 1993 |
| 51.246.0.0/15 | 131k | RIPE NCC | GB | 1st Sept 1993 |
| 51.250.128.0/17 | 32.8k | RIPE NCC |  RU | 1st Sept 1993 |
| 51.251.0.0/16 | 65.5k | RIPE NCC | GB | 1st Sept 1993 |
| 51.33.0.0/16 | 65.5k | RIPE NCC | GB | 1st Sept 1993 |
| 51.62.0.0/15 | 131k | RIPE NCC | GB | 1st Sept 1993 |
| 51.65.0.0/16 | 65.5k | RIPE NCC | GB | 1st Sept 1993 |
| 51.66.0.0/15 | 131k | RIPE NCC | GB | 1st Sept 1993 |
| 51.71.0.0/16 | 65.5k | RIPE NCC | GB | 1st Sept 1993 |
| 52.119.0.0/24 | 256 | ARIN | US | 27th Apr 2016 |
| 52.119.13.0/24 | 256 | ARIN | US | 1st Jun 2016 |
| 52.119.3.0/24 | 256 | ARIN | US | 13th Nov 2025 |
| 52.124.128.0/17 | 32.8k | ARIN | US | 9th Aug 2016 |
| 52.124.2.0/24 | 256 | ARIN | US | 30th Mar 2016 |
| 52.124.62.0/24 | 256 | ARIN |  CA | 26th Apr 2016 |
| 52.124.63.0/24 | 256 | ARIN | US | 22nd Mar 2016 |
| 52.128.128.0/19 | 8.2k | APNIC |  SG | 23rd Jun 2016 |
| 52.128.28.0/24 | 256 | ARIN | US | 4th May 2017 |
| 52.129.11.0/24 | 256 | ARIN | CA | 11th Feb 2016 |
| 52.129.128.0/17 | 32.8k | ARIN | US | 9th Aug 2016 |
| 52.129.14.0/23 | 512 | ARIN | US | 4th Feb 2016 |
| 52.129.23.0/24 | 256 | ARIN | US | 7th Mar 2016 |
| 52.132.0.0/14 | 262k | ARIN | US | 24th Nov 2015 |
| 52.144.16.0/21 | 2k | ARIN | US | 4th Apr 2016 |
| 52.144.30.0/24 | 256 | ARIN | US | 2nd Oct 2026 |
| 52.145.0.0/16 | 65.5k | ARIN | US | 24th Nov 2015 |
| 52.223.192.0/18 | 16.4k | ARIN | US | 2nd Sept 2015 |
| 54.1.0.0/16 | 65.5k | ARIN | US | 17th Mar 1992 |
| 54.10.0.0/15 | 131k | ARIN | US | 17th Mar 1992 |
| 54.101.0.0/16 | 65.5k | ARIN | US | 17th Mar 1992 |
| 54.103.0.0/16 | 65.5k | ARIN | US | 17th Mar 1992 |
| 54.105.0.0/16 | 65.5k | ARIN | US | 17th Mar 1992 |
| 54.110.0.0/16 | 65.5k | ARIN | US | 17th Mar 1992 |
| 54.120.0.0/16 | 65.5k | ARIN | US | 17th Mar 1992 |
| 54.125.0.0/16 | 65.5k | ARIN | US | 17th Mar 1992 |
| 54.129.0.0/16 | 65.5k | ARIN | US | 17th Mar 1992 |
| 54.13.0.0/16 | 65.5k | ARIN | US | 17th Mar 1992 |
| 54.136.0.0/15 | 131k | ARIN | US | 27th Dec 2021 |
| 54.14.0.0/16 | 65.5k | ARIN | US | 17th Mar 1992 |
| 54.140.0.0/14 | 262k | ARIN | US | 17th Mar 1992 |
| 54.23.0.0/16 | 65.5k | ARIN | US | 17th Mar 1992 |
| 54.24.0.0/16 | 65.5k | ARIN | US | 17th Mar 1992 |