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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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 |
|---|---|---|---|---|
| 151.175.0.0/16 | 65.5k | RIPE NCC |  EU | 1st Sept 1993 |
| 151.178.0.0/16 | 65.5k | APNIC |  AU | 17th Sept 1991 |
| 151.180.0.0/16 | 65.5k | RIPE NCC |  GB | 17th Sept 1991 |
| 151.181.128.0/19 | 8.2k | ARIN |  US | 17th Sept 1991 |
| 151.181.176.0/20 | 4.1k | ARIN | US | 17th Sept 1991 |
| 151.184.0.0/16 | 65.5k | RIPE NCC |  NL | 17th Sept 1991 |
| 151.185.0.0/19 | 8.2k | RIPE NCC | US | 17th Sept 1991 |
| 151.185.128.0/18 | 16.4k | ARIN | US | 8th Jul 2026 |
| 151.2.20.0/22 | 1k | RIPE NCC |  IT | 13th May 1991 |
| 151.2.24.0/21 | 2k | RIPE NCC | IT | 13th May 1991 |
| 151.209.0.0/16 | 65.5k | ARIN | US | 25th Sept 1991 |
| 151.210.64.0/19 | 8.2k | ARIN | US | 31st Jul 2026 |
| 151.211.0.0/16 | 65.5k | RIPE NCC | GB | 25th Sept 1991 |
| 151.212.0.0/16 | 65.5k | RIPE NCC | GB | 25th Sept 1991 |
| 151.216.112.0/21 | 2k | RIPE NCC |  AT | 12th Aug 2026 |
| 151.216.120.0/22 | 1k | RIPE NCC | AT | 12th Aug 2026 |
| 151.216.6.0/24 | 256 | RIPE NCC |  PL | 5th Aug 2026 |
| 151.237.236.0/24 | 256 | RIPE NCC | GB | 16th Aug 2012 |
| 151.237.248.0/21 | 2k | RIPE NCC |  DE | 16th Aug 2012 |
| 151.237.8.0/23 | 512 | RIPE NCC | GB | 16th Aug 2012 |
| 151.249.96.0/21 | 2k | RIPE NCC |  UA | 21st Aug 2012 |
| 151.252.96.0/21 | 2k | RIPE NCC |  PS | 23rd Aug 2012 |
| 151.85.0.0/16 | 65.5k | RIPE NCC | IT | 13th May 1991 |
| 151.86.0.0/16 | 65.5k | RIPE NCC | IT | 13th May 1991 |
| 151.94.0.0/16 | 65.5k | RIPE NCC | IT | 13th May 1991 |
| 152.100.0.0/16 | 65.5k | ARIN | US | 12th Sept 1991 |
| 152.103.0.0/16 | 65.5k | APNIC |  HK | 23rd Sept 1993 |
| 152.109.0.0/16 | 65.5k | AFRINIC |  ZA | 29th Mar 1993 |
| 152.114.197.0/24 | 256 | RIPE NCC |  ES | 1st Jan 1984 |
| 152.114.198.0/23 | 512 | RIPE NCC | ES | 1st Jan 1984 |
| 152.114.212.0/22 | 1k | RIPE NCC | GB | 1st Jan 1984 |
| 152.114.228.0/22 | 1k | RIPE NCC |  SA | 1st Jan 1984 |
| 152.116.0.0/16 | 65.5k | ARIN | US | 13th Aug 1991 |
| 152.117.32.0/20 | 4.1k | ARIN | US | 13th Aug 1991 |
| 152.139.0.0/16 | 65.5k | LACNIC |  CL | 21st Aug 1991 |
| 152.140.0.0/15 | 131k | ARIN | US | 22nd Aug 1991 |
| 152.142.0.0/16 | 65.5k | ARIN | US | 22nd Aug 1991 |
| 152.144.0.0/16 | 65.5k | ARIN | US | 22nd Aug 1991 |
| 152.146.0.0/16 | 65.5k | ARIN | US | 23rd Aug 1991 |
| 152.147.0.0/16 | 65.5k | APNIC | AU | 23rd Aug 1991 |
| 152.150.0.0/16 | 65.5k | RIPE NCC | GB | 1st Sept 1993 |
| 152.153.0.0/16 | 65.5k | APNIC |  NZ | 4th Sept 1991 |
| 152.159.0.0/16 | 65.5k | ARIN | US | 18th Mar 1992 |
| 152.161.0.0/16 | 65.5k | ARIN | US | 1st Apr 1992 |
| 152.162.0.0/16 | 65.5k | ARIN | US | 1st Apr 1992 |
| 152.224.0.0/15 | 131k | ARIN | US | 23rd Sept 1991 |
| 152.228.96.0/19 | 8.2k | ARIN | US | 30th Sept 1991 |
| 152.234.128.0/19 | 8.2k | RIPE NCC |  AE | 6th Mar 2025 |
| 152.234.192.0/18 | 16.4k | RIPE NCC | US | 6th Mar 2025 |
| 152.235.0.0/17 | 32.8k | ARIN | US | 9th Feb 2026 |