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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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 Japan
1,447 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 163.227.17.0/24 | 256 | APNIC |  JP | 16th Apr 1993 |
| 163.227.221.0/24 | 256 | APNIC | JP | 16th Apr 1993 |
| 163.227.225.0/24 | 256 | APNIC | JP | 16th Apr 1993 |
| 163.227.226.0/23 | 512 | APNIC | JP | 16th Apr 1993 |
| 163.227.233.0/24 | 256 | APNIC | JP | 16th Apr 1993 |
| 163.227.234.0/24 | 256 | APNIC | JP | 16th Apr 1993 |
| 163.227.241.0/24 | 256 | APNIC | JP | 16th Apr 1993 |
| 163.227.242.0/23 | 512 | APNIC | JP | 16th Apr 1993 |
| 163.227.254.0/24 | 256 | APNIC | JP | 16th Apr 1993 |
| 163.227.4.0/23 | 512 | APNIC | JP | 8th Apr 2025 |
| 163.47.19.0/24 | 256 | APNIC | JP | 24th Jul 1992 |
| 163.47.23.0/24 | 256 | APNIC | JP | 24th Jul 1992 |
| 163.47.24.0/24 | 256 | APNIC | JP | 24th Jul 1992 |
| 163.47.29.0/24 | 256 | APNIC | JP | 24th Jul 1992 |
| 163.50.0.0/16 | 65.5k | APNIC | JP | 24th Jul 1992 |
| 163.56.0.0/16 | 65.5k | APNIC | JP | 24th Jul 1992 |
| 163.60.0.0/16 | 65.5k | APNIC | JP | 24th Jul 1992 |
| 163.61.37.0/24 | 256 | APNIC | JP | 2nd Feb 2025 |
| 165.101.0.0/22 | 1k | APNIC | JP | 11th May 1993 |
| 165.102.0.0/16 | 65.5k | APNIC | JP | 11th May 1993 |
| 165.96.0.0/16 | 65.5k | APNIC | JP | 10th May 1993 |
| 166.118.0.0/16 | 65.5k | APNIC | JP | 27th Dec 1993 |
| 175.100.224.0/19 | 8.2k | APNIC | JP | 4th Jan 2010 |
| 175.103.130.0/23 | 512 | APNIC | JP | 4th Jan 2010 |
| 175.103.132.0/23 | 512 | APNIC | JP | 4th Jan 2010 |
| 175.103.134.0/23 | 512 | APNIC | JP | 4th Jan 2010 |
| 175.103.136.0/21 | 2k | APNIC | JP | 4th Jan 2010 |
| 175.103.152.0/22 | 1k | APNIC | JP | 4th Jan 2010 |
| 175.103.156.0/23 | 512 | APNIC | JP | 4th Jan 2010 |
| 175.103.158.0/24 | 256 | APNIC | JP | 4th Jan 2010 |
| 175.103.159.0/24 | 256 | APNIC | JP | 4th Jan 2010 |
| 175.103.160.0/22 | 1k | APNIC | JP | 4th Jan 2010 |
| 175.103.166.0/23 | 512 | APNIC | JP | 4th Jan 2010 |
| 175.103.168.0/22 | 1k | APNIC | JP | 4th Jan 2010 |
| 175.103.172.0/23 | 512 | APNIC | JP | 4th Jan 2010 |
| 175.103.174.0/23 | 512 | APNIC | JP | 4th Jan 2010 |
| 175.103.178.0/23 | 512 | APNIC | JP | 4th Jan 2010 |
| 175.103.192.0/20 | 4.1k | APNIC | JP | 4th Jan 2010 |
| 175.103.208.0/21 | 2k | APNIC | JP | 4th Jan 2010 |
| 175.103.4.0/22 | 1k | APNIC | JP | 4th Jan 2010 |
| 175.179.64.0/19 | 8.2k | APNIC | JP | 27th Jan 2010 |
| 175.28.63.0/24 | 256 | APNIC | JP | 11th Dec 2009 |
| 176.118.178.0/24 | 256 | RIPE NCC | JP | 30th Sept 2025 |
| 180.131.64.0/21 | 2k | APNIC | JP | 20th Aug 2009 |
| 180.131.72.0/22 | 1k | APNIC | JP | 20th Aug 2009 |
| 180.131.76.0/22 | 1k | APNIC | JP | 20th Aug 2009 |
| 180.131.80.0/23 | 512 | APNIC | JP | 20th Aug 2009 |
| 180.131.82.0/24 | 256 | APNIC | JP | 20th Aug 2009 |
| 180.131.83.0/24 | 256 | APNIC | JP | 20th Aug 2009 |
| 180.131.84.0/22 | 1k | APNIC | JP | 20th Aug 2009 |