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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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 ARIN, largest first.
Unannounced blocks in United States
26,302 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 204.128.229.0/24 | 256 | ARIN |  US | 21st Feb 1995 |
| 204.128.230.0/24 | 256 | ARIN | US | 21st Feb 1995 |
| 204.128.231.0/24 | 256 | ARIN | US | 22nd Feb 1995 |
| 204.128.239.0/24 | 256 | ARIN | US | 23rd Feb 1995 |
| 204.128.244.0/24 | 256 | ARIN | US | 23rd Feb 1995 |
| 204.128.245.0/24 | 256 | ARIN | US | 27th Feb 1995 |
| 204.128.246.0/24 | 256 | ARIN | US | 23rd Feb 1995 |
| 204.128.247.0/24 | 256 | ARIN | US | 28th Feb 1995 |
| 204.128.248.0/24 | 256 | ARIN | US | 28th Feb 1995 |
| 204.128.251.0/24 | 256 | ARIN | US | 28th Feb 1995 |
| 204.128.253.0/24 | 256 | ARIN | US | 4th Mar 1995 |
| 204.128.254.0/24 | 256 | ARIN | US | 4th Mar 1995 |
| 204.128.255.0/24 | 256 | ARIN | US | 4th Mar 1995 |
| 204.128.32.0/20 | 4.1k | ARIN | US | 25th Aug 1994 |
| 204.128.48.0/22 | 1k | ARIN | US | 25th Aug 1994 |
| 204.128.56.0/21 | 2k | ARIN | US | 10th Feb 2009 |
| 204.13.158.0/24 | 256 | ARIN | US | 2nd Mar 2018 |
| 204.13.228.0/23 | 512 | ARIN | US | 13th Nov 2017 |
| 204.13.248.0/22 | 1k | ARIN | US | 10th May 2005 |
| 204.13.76.0/24 | 256 | ARIN | US | 31st May 2017 |
| 204.130.128.0/24 | 256 | ARIN | US | 9th Nov 1994 |
| 204.130.129.0/24 | 256 | ARIN | US | 1st Jul 2026 |
| 204.130.131.0/24 | 256 | ARIN | US | 10th Nov 1994 |
| 204.130.134.0/24 | 256 | ARIN | US | 10th Nov 1994 |
| 204.130.136.0/24 | 256 | ARIN | US | 10th Nov 1994 |
| 204.130.137.0/24 | 256 | ARIN | US | 10th Nov 1994 |
| 204.130.138.0/24 | 256 | ARIN | US | 10th Nov 1994 |
| 204.130.139.0/24 | 256 | ARIN | US | 10th Nov 1994 |
| 204.130.141.0/24 | 256 | ARIN | US | 10th Nov 1994 |
| 204.130.142.0/24 | 256 | ARIN | US | 15th Nov 1994 |
| 204.130.143.0/24 | 256 | ARIN | US | 15th Nov 1994 |
| 204.130.144.0/24 | 256 | ARIN | US | 15th Nov 1994 |
| 204.130.145.0/24 | 256 | ARIN | US | 15th Nov 1994 |
| 204.130.146.0/24 | 256 | ARIN | US | 15th Nov 1994 |
| 204.130.148.0/24 | 256 | ARIN | US | 15th Nov 1994 |
| 204.130.149.0/24 | 256 | ARIN | US | 15th Nov 1994 |
| 204.130.150.0/24 | 256 | ARIN | US | 15th Nov 1994 |
| 204.130.152.0/24 | 256 | ARIN | US | 16th Nov 1994 |
| 204.130.153.0/24 | 256 | ARIN | US | 16th Nov 1994 |
| 204.130.156.0/24 | 256 | ARIN | US | 16th Nov 1994 |
| 204.130.157.0/24 | 256 | ARIN | US | 16th Nov 1994 |
| 204.130.159.0/24 | 256 | ARIN | US | 16th Nov 1994 |
| 204.130.16.0/20 | 4.1k | ARIN | US | 24th Aug 1994 |
| 204.130.160.0/24 | 256 | ARIN | US | 16th Nov 1994 |
| 204.130.161.0/24 | 256 | ARIN | US | 16th Nov 1994 |
| 204.130.162.0/24 | 256 | ARIN | US | 16th Nov 1994 |
| 204.130.163.0/24 | 256 | ARIN | US | 16th Nov 1994 |
| 204.130.164.0/24 | 256 | ARIN | US | 16th Nov 1994 |
| 204.130.165.0/24 | 256 | ARIN | US | 16th Nov 1994 |
| 204.130.166.0/24 | 256 | ARIN | US | 16th Nov 1994 |