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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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.
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Countries with unannounced space registered through ARIN, largest first.
Unannounced blocks in United States
26,295 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 192.42.148.0/24 | 256 | ARIN |  US | 11th Oct 1988 |
| 192.42.149.0/24 | 256 | ARIN | US | 11th Oct 1988 |
| 192.42.150.0/24 | 256 | ARIN | US | 11th Oct 1988 |
| 192.42.154.0/24 | 256 | ARIN | US | 14th Oct 1988 |
| 192.42.155.0/24 | 256 | ARIN | US | 21st Jul 2014 |
| 192.42.157.0/24 | 256 | ARIN | US | 14th Oct 1988 |
| 192.42.158.0/24 | 256 | ARIN | US | 18th Oct 1988 |
| 192.42.159.0/24 | 256 | ARIN | US | 18th Oct 1988 |
| 192.42.172.0/24 | 256 | ARIN | US | 18th Oct 1988 |
| 192.42.207.0/24 | 256 | ARIN | US | 25th Oct 1988 |
| 192.42.208.0/20 | 4.1k | ARIN | US | 25th Oct 1988 |
| 192.42.224.0/21 | 2k | ARIN | US | 25th Oct 1988 |
| 192.42.232.0/22 | 1k | ARIN | US | 25th Oct 1988 |
| 192.42.236.0/24 | 256 | ARIN | US | 25th Oct 1988 |
| 192.42.238.0/24 | 256 | ARIN | US | 27th Oct 1988 |
| 192.42.240.0/24 | 256 | ARIN | US | 27th Oct 1988 |
| 192.42.242.0/24 | 256 | ARIN | US | 31st Oct 1988 |
| 192.42.243.0/24 | 256 | ARIN | US | 13th Jan 1989 |
| 192.42.244.0/24 | 256 | ARIN | US | 2nd Nov 1988 |
| 192.42.245.0/24 | 256 | ARIN | US | 2nd Nov 1988 |
| 192.42.247.0/24 | 256 | ARIN | US | 2nd Nov 1988 |
| 192.42.249.0/24 | 256 | ARIN | US | 4th Nov 1988 |
| 192.42.250.0/24 | 256 | ARIN | US | 4th Nov 1988 |
| 192.42.32.0/21 | 2k | ARIN | US | 8th Aug 1988 |
| 192.42.40.0/24 | 256 | ARIN | US | 8th Aug 1988 |
| 192.42.49.0/24 | 256 | ARIN | US | 1st Jul 2026 |
| 192.42.50.0/24 | 256 | ARIN | US | 2nd Jul 2026 |
| 192.42.51.0/24 | 256 | ARIN | US | 2nd Jul 2026 |
| 192.42.56.0/24 | 256 | ARIN | US | 19th Aug 1988 |
| 192.42.57.0/24 | 256 | ARIN | US | 19th Aug 1988 |
| 192.42.58.0/24 | 256 | ARIN | US | 19th Aug 1988 |
| 192.42.59.0/24 | 256 | ARIN | US | 19th Aug 1988 |
| 192.42.66.0/24 | 256 | ARIN | US | 24th Aug 1988 |
| 192.42.67.0/24 | 256 | ARIN | US | 24th Aug 1988 |
| 192.42.70.0/24 | 256 | ARIN | US | 26th Aug 1988 |
| 192.42.71.0/24 | 256 | ARIN | US | 16th Jul 2014 |
| 192.42.75.0/24 | 256 | ARIN | US | 29th Aug 1988 |
| 192.42.76.0/24 | 256 | ARIN | US | 29th Aug 1988 |
| 192.42.77.0/24 | 256 | ARIN | US | 29th Aug 1988 |
| 192.42.78.0/24 | 256 | ARIN | US | 29th Aug 1988 |
| 192.42.79.0/24 | 256 | ARIN | US | 29th Aug 1988 |
| 192.42.8.0/24 | 256 | ARIN | US | 5th Aug 1988 |
| 192.42.9.0/24 | 256 | ARIN | US | 8th Aug 1988 |
| 192.42.91.0/24 | 256 | ARIN | US | 9th Sept 1988 |
| 192.42.94.0/24 | 256 | ARIN | US | 13th Sept 1988 |
| 192.42.96.0/24 | 256 | ARIN | US | 17th Jul 2014 |
| 192.43.1.0/24 | 256 | ARIN | US | 4th Oct 1988 |
| 192.43.128.0/20 | 4.1k | ARIN | US | 4th Oct 1988 |
| 192.43.144.0/22 | 1k | ARIN | US | 4th Oct 1988 |
| 192.43.148.0/23 | 512 | ARIN | US | 4th Oct 1988 |