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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
85,195 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 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 |
| 192.52.100.0/24 | 256 | ARIN |  US | 7th Apr 1989 |
| 192.52.101.0/24 | 256 | ARIN | US | 7th Apr 1989 |
| 192.52.102.0/24 | 256 | ARIN | US | 7th Apr 1989 |
| 192.52.103.0/24 | 256 | ARIN | US | 7th Apr 1989 |
| 192.52.104.0/24 | 256 | ARIN | US | 7th Apr 1989 |
| 192.52.105.0/24 | 256 | ARIN | US | 7th Apr 1989 |
| 192.52.107.0/24 | 256 | ARIN | US | 11th Apr 1989 |
| 192.52.110.0/24 | 256 | ARIN | US | 14th Apr 1989 |
| 192.52.113.0/24 | 256 | ARIN | US | 14th Apr 1989 |
| 192.52.116.0/24 | 256 | ARIN | US | 14th Apr 1989 |
| 192.52.118.0/24 | 256 | ARIN | US | 1st Oct 2014 |
| 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 |
| 192.52.151.0/24 | 256 | ARIN | US | 19th Apr 1989 |
| 192.52.152.0/24 | 256 | RIPE NCC |  NL | 20th Apr 1989 |
| 192.52.153.0/24 | 256 | ARIN | US | 20th Apr 1989 |
| 192.52.154.0/24 | 256 | ARIN | US | 20th Apr 1989 |
| 192.52.157.0/24 | 256 | ARIN | US | 21st Apr 1989 |
| 192.52.159.0/24 | 256 | RIPE NCC |  DE | 22nd Apr 1989 |
| 192.52.160.0/24 | 256 | RIPE NCC | DE | 22nd Apr 1989 |
| 192.52.161.0/24 | 256 | RIPE NCC |  GB | 24th Apr 1989 |
| 192.52.170.0/24 | 256 | ARIN | US | 25th Apr 1989 |
| 192.52.171.0/24 | 256 | APNIC |  AU | 26th Apr 1989 |
| 192.52.172.0/24 | 256 | APNIC | AU | 26th Apr 1989 |
| 192.52.173.0/24 | 256 | APNIC | AU | 26th Apr 1989 |
| 192.52.174.0/24 | 256 | APNIC | AU | 26th Apr 1989 |
| 192.52.175.0/24 | 256 | APNIC | AU | 26th Apr 1989 |
| 192.52.176.0/24 | 256 | APNIC | AU | 26th Apr 1989 |
| 192.52.180.0/24 | 256 | ARIN | US | 27th Apr 1989 |
| 192.52.181.0/24 | 256 | ARIN | US | 27th Apr 1989 |
| 192.52.182.0/24 | 256 | ARIN | US | 27th Apr 1989 |
| 192.52.184.0/24 | 256 | ARIN | US | 3rd May 1989 |