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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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 the most unannounced blocks, largest first.
Unannounced blocks
85,108 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 192.100.17.0/24 | 256 | ARIN |  US | 13th Mar 1991 |
| 192.100.174.0/24 | 256 | LACNIC |  MX | 29th Jan 1993 |
| 192.100.178.0/24 | 256 | LACNIC | MX | 29th Jan 1993 |
| 192.100.18.0/24 | 256 | RIPE NCC |  FR | 13th Mar 1991 |
| 192.100.183.0/24 | 256 | LACNIC | MX | 6th Dec 1993 |
| 192.100.184.0/23 | 512 | LACNIC | MX | 28th Apr 1993 |
| 192.100.19.0/24 | 256 | ARIN | US | 14th Mar 1991 |
| 192.100.190.0/24 | 256 | LACNIC | MX | 21st Apr 1994 |
| 192.100.2.0/24 | 256 | APNIC |  KR | 11th Mar 1991 |
| 192.100.20.0/24 | 256 | ARIN | US | 14th Mar 1991 |
| 192.100.203.0/24 | 256 | LACNIC | MX | 16th Feb 1994 |
| 192.100.205.0/24 | 256 | LACNIC | MX | 24th Feb 1994 |
| 192.100.207.0/24 | 256 | LACNIC | MX | 14th Mar 1994 |
| 192.100.209.0/24 | 256 | LACNIC | MX | 14th Mar 1994 |
| 192.100.21.0/24 | 256 | ARIN | US | 14th Mar 1991 |
| 192.100.210.0/24 | 256 | LACNIC | MX | 25th Mar 1994 |
| 192.100.211.0/24 | 256 | LACNIC | MX | 31st Mar 1994 |
| 192.100.212.0/24 | 256 | LACNIC | MX | 24th Mar 1994 |
| 192.100.213.0/24 | 256 | LACNIC | MX | 10th May 1994 |
| 192.100.214.0/23 | 512 | LACNIC |  BR | 24th Oct 2025 |
| 192.100.216.0/24 | 256 | LACNIC | MX | 25th Mar 1994 |
| 192.100.217.0/24 | 256 | LACNIC | MX | 28th Mar 1994 |
| 192.100.218.0/24 | 256 | LACNIC | MX | 21st Apr 1994 |
| 192.100.219.0/24 | 256 | LACNIC | MX | 21st Apr 1994 |
| 192.100.221.0/24 | 256 | LACNIC | MX | 6th May 1994 |
| 192.100.222.0/24 | 256 | LACNIC | MX | 6th May 1994 |
| 192.100.226.0/24 | 256 | LACNIC | MX | 3rd Aug 2007 |
| 192.100.227.0/24 | 256 | LACNIC | MX | 3rd Aug 2007 |
| 192.100.23.0/24 | 256 | RIPE NCC |  AT | 18th Mar 1991 |
| 192.100.231.0/24 | 256 | LACNIC | MX | 10th May 1994 |
| 192.100.232.0/23 | 512 | LACNIC | MX | 16th Feb 2006 |
| 192.100.235.0/24 | 256 | LACNIC | MX | 10th May 1994 |
| 192.100.236.0/24 | 256 | LACNIC | MX | 26th May 1994 |
| 192.100.237.0/24 | 256 | LACNIC | MX | 26th May 1994 |
| 192.100.238.0/23 | 512 | LACNIC | MX | 26th May 1994 |
| 192.100.24.0/24 | 256 | RIPE NCC | AT | 18th Mar 1991 |
| 192.100.240.0/24 | 256 | LACNIC | MX | 26th May 1994 |
| 192.100.241.0/24 | 256 | LACNIC | MX | 26th Dec 1997 |
| 192.100.242.0/23 | 512 | LACNIC | MX | 26th Dec 1997 |
| 192.100.245.0/24 | 256 | LACNIC | MX | 25th May 1994 |
| 192.100.246.0/24 | 256 | LACNIC | MX | 25th May 1994 |
| 192.100.249.0/24 | 256 | LACNIC | MX | 3rd Jun 1994 |
| 192.100.25.0/24 | 256 | RIPE NCC | AT | 18th Mar 1991 |
| 192.100.250.0/24 | 256 | LACNIC | MX | 3rd Jun 1994 |
| 192.100.26.0/24 | 256 | ARIN | US | 18th Mar 1991 |
| 192.100.27.0/24 | 256 | ARIN | US | 19th Mar 1991 |
| 192.100.28.0/24 | 256 | ARIN | US | 19th Mar 1991 |
| 192.100.3.0/24 | 256 | ARIN | US | 11th Mar 1991 |
| 192.100.31.0/24 | 256 | ARIN | US | 22nd Mar 1991 |
| 192.100.32.0/21 | 2k | ARIN | US | 22nd Mar 1991 |