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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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 |
|---|---|---|---|---|
| 203.121.183.0/24 | 256 | APNIC |  JP | 17th Jan 2003 |
| 203.121.184.0/24 | 256 | APNIC | JP | 17th Jan 2003 |
| 203.121.187.0/24 | 256 | APNIC | JP | 17th Jan 2003 |
| 203.121.189.0/24 | 256 | APNIC | JP | 17th Jan 2003 |
| 203.121.190.0/23 | 512 | APNIC | JP | 17th Jan 2003 |
| 203.124.6.0/23 | 512 | APNIC | JP | 26th Mar 2007 |
| 203.129.160.0/19 | 8.2k | APNIC | JP | 15th Mar 2005 |
| 203.14.212.0/24 | 256 | APNIC | JP | 20th Jul 2005 |
| 203.152.10.0/24 | 256 | APNIC | JP | 15th Jan 2003 |
| 203.152.15.0/24 | 256 | APNIC | JP | 15th Jan 2003 |
| 203.152.21.0/24 | 256 | APNIC | JP | 15th Jan 2003 |
| 203.152.23.0/24 | 256 | APNIC | JP | 15th Jan 2003 |
| 203.152.38.0/24 | 256 | APNIC | JP | 15th Jan 2003 |
| 203.152.41.0/24 | 256 | APNIC | JP | 15th Jan 2003 |
| 203.152.45.0/24 | 256 | APNIC | JP | 15th Jan 2003 |
| 203.152.46.0/24 | 256 | APNIC | JP | 15th Jan 2003 |
| 203.152.5.0/24 | 256 | APNIC | JP | 15th Jan 2003 |
| 203.152.51.0/24 | 256 | APNIC | JP | 15th Jan 2003 |
| 203.152.52.0/24 | 256 | APNIC | JP | 15th Jan 2003 |
| 203.152.54.0/24 | 256 | APNIC | JP | 15th Jan 2003 |
| 203.152.59.0/24 | 256 | APNIC | JP | 15th Jan 2003 |
| 203.152.60.0/24 | 256 | APNIC | JP | 15th Jan 2003 |
| 203.152.61.0/24 | 256 | APNIC | JP | 15th Jan 2003 |
| 203.17.188.0/24 | 256 | APNIC | JP | 26th Jul 1995 |
| 203.17.52.0/24 | 256 | APNIC | JP | 11th Jul 1995 |
| 203.170.90.0/23 | 512 | APNIC | JP | 4th Apr 2024 |
| 203.173.80.0/21 | 2k | APNIC | JP | 21st Apr 2006 |
| 203.175.16.0/20 | 4.1k | APNIC | JP | 27th Apr 2006 |
| 203.190.28.0/22 | 1k | APNIC | JP | 19th May 2008 |
| 203.196.88.0/23 | 512 | APNIC | JP | 10th Jun 2008 |
| 203.196.91.0/24 | 256 | APNIC | JP | 16th Jun 2008 |
| 203.222.224.0/19 | 8.2k | APNIC | JP | 26th Apr 2006 |
| 203.223.64.0/23 | 512 | APNIC | JP | 12th Apr 2001 |
| 203.223.66.0/23 | 512 | APNIC | JP | 13th Nov 2001 |
| 203.223.68.0/22 | 1k | APNIC | JP | 13th Nov 2001 |
| 203.223.72.0/21 | 2k | APNIC | JP | 13th Nov 2001 |
| 203.28.151.0/24 | 256 | APNIC | JP | 10th Apr 2008 |
| 203.34.81.0/24 | 256 | APNIC | JP | 20th Jun 2005 |
| 203.77.184.0/21 | 2k | APNIC | JP | 20th Dec 2005 |
| 203.95.16.0/21 | 2k | APNIC | JP | 23rd Mar 2006 |
| 203.99.0.0/21 | 2k | APNIC | JP | 8th Mar 2006 |
| 204.231.230.0/24 | 256 | ARIN | JP | 21st Apr 1995 |
| 204.231.251.0/24 | 256 | ARIN | JP | 21st Apr 1995 |
| 204.231.252.0/24 | 256 | ARIN | JP | 21st Apr 1995 |
| 204.79.157.0/24 | 256 | ARIN | JP | 14th Dec 1994 |
| 204.79.158.0/24 | 256 | ARIN | JP | 14th Dec 1994 |
| 204.79.218.0/24 | 256 | ARIN | JP | 19th Dec 1994 |
| 210.17.161.0/24 | 256 | APNIC | JP | 24th Jul 2002 |
| 210.211.32.0/20 | 4.1k | APNIC | JP | 5th Jul 2006 |
| 210.24.132.0/24 | 256 | APNIC | JP | 16th Dec 1996 |