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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
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Countries with unannounced space registered through APNIC, largest first.
Unannounced blocks in Japan
1,422 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 192.51.230.0/24 | 256 | APNIC |  JP | 6th Aug 1993 |
| 192.51.231.0/24 | 256 | APNIC | JP | 6th Aug 1993 |
| 192.51.232.0/24 | 256 | APNIC | JP | 6th Aug 1993 |
| 192.51.233.0/24 | 256 | APNIC | JP | 21st Feb 1989 |
| 192.51.234.0/24 | 256 | APNIC | JP | 6th Aug 1993 |
| 192.51.235.0/24 | 256 | APNIC | JP | 6th Aug 1993 |
| 192.51.236.0/24 | 256 | APNIC | JP | 6th Aug 1993 |
| 192.51.237.0/24 | 256 | APNIC | JP | 6th Aug 1993 |
| 192.51.238.0/24 | 256 | APNIC | JP | 6th Aug 1993 |
| 192.51.239.0/24 | 256 | APNIC | JP | 6th Aug 1993 |
| 192.51.241.0/24 | 256 | APNIC | JP | 6th Aug 1993 |
| 192.51.242.0/24 | 256 | APNIC | JP | 6th Aug 1993 |
| 192.51.243.0/24 | 256 | APNIC | JP | 6th Aug 1993 |
| 192.51.244.0/24 | 256 | APNIC | JP | 6th Aug 1993 |
| 192.51.245.0/24 | 256 | APNIC | JP | 6th Aug 1993 |
| 192.51.246.0/24 | 256 | APNIC | JP | 6th Aug 1993 |
| 192.51.247.0/24 | 256 | APNIC | JP | 6th Aug 1993 |
| 192.51.248.0/24 | 256 | APNIC | JP | 6th Aug 1993 |
| 192.51.249.0/24 | 256 | APNIC | JP | 6th Aug 1993 |
| 192.51.250.0/24 | 256 | APNIC | JP | 7th May 1993 |
| 192.51.251.0/24 | 256 | APNIC | JP | 7th May 1993 |
| 192.51.253.0/24 | 256 | APNIC | JP | 6th Aug 1993 |
| 192.51.255.0/24 | 256 | APNIC | JP | 21st Feb 1989 |
| 192.51.32.0/22 | 1k | APNIC | JP | 2nd Aug 1993 |
| 192.51.36.0/24 | 256 | APNIC | JP | 2nd Aug 1993 |
| 192.51.37.0/24 | 256 | APNIC | JP | 21st Feb 1989 |
| 192.51.38.0/24 | 256 | APNIC | JP | 21st Feb 1989 |
| 192.51.44.0/24 | 256 | APNIC | JP | 2nd Aug 1993 |
| 192.51.45.0/24 | 256 | APNIC | JP | 2nd Aug 1993 |
| 192.51.46.0/24 | 256 | APNIC | JP | 2nd Aug 1993 |
| 192.51.47.0/24 | 256 | APNIC | JP | 2nd Aug 1993 |
| 192.51.49.0/24 | 256 | APNIC | JP | 21st Feb 1989 |
| 192.51.50.0/24 | 256 | APNIC | JP | 21st Feb 1989 |
| 192.51.51.0/24 | 256 | APNIC | JP | 21st Feb 1989 |
| 192.51.52.0/23 | 512 | APNIC | JP | 11th Jul 1994 |
| 192.51.56.0/24 | 256 | APNIC | JP | 12th Oct 2001 |
| 192.51.57.0/24 | 256 | APNIC | JP | 21st Feb 1989 |
| 192.51.58.0/23 | 512 | APNIC | JP | 21st Feb 1989 |
| 192.51.60.0/23 | 512 | APNIC | JP | 21st Feb 1989 |
| 192.51.62.0/24 | 256 | APNIC | JP | 9th Feb 1995 |
| 192.51.63.0/24 | 256 | APNIC | JP | 21st Feb 1989 |
| 192.51.64.0/18 | 16.4k | APNIC | JP | 21st Feb 1989 |
| 192.52.119.0/24 | 256 | APNIC | JP | 24th Jan 2011 |
| 192.52.120.0/21 | 2k | APNIC | JP | 24th Jan 2011 |
| 192.52.128.0/20 | 4.1k | APNIC | JP | 24th Jan 2011 |
| 192.52.144.0/22 | 1k | APNIC | JP | 24th Jan 2011 |
| 192.52.148.0/23 | 512 | APNIC | JP | 24th Jan 2011 |
| 192.52.150.0/24 | 256 | APNIC | JP | 24th Jan 2011 |
| 192.55.118.0/24 | 256 | APNIC | JP | 31st Jul 1989 |
| 192.76.252.0/23 | 512 | APNIC | JP | 3rd Feb 2011 |