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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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 |
|---|---|---|---|---|
| 204.238.155.0/24 | 256 | ARIN |  US | 18th May 1995 |
| 204.238.156.0/24 | 256 | ARIN | US | 18th May 1995 |
| 204.238.157.0/24 | 256 | ARIN | US | 19th May 1995 |
| 204.238.158.0/24 | 256 | ARIN | US | 22nd May 1995 |
| 204.238.159.0/24 | 256 | ARIN | US | 4th Oct 2022 |
| 204.238.16.0/24 | 256 | ARIN | US | 10th Feb 1995 |
| 204.238.160.0/24 | 256 | ARIN | US | 22nd May 1995 |
| 204.238.161.0/24 | 256 | ARIN | US | 22nd May 1995 |
| 204.238.162.0/24 | 256 | ARIN | US | 22nd May 1995 |
| 204.238.163.0/24 | 256 | ARIN | US | 22nd May 1995 |
| 204.238.164.0/24 | 256 | ARIN | US | 22nd May 1995 |
| 204.238.165.0/24 | 256 | ARIN | US | 22nd May 1995 |
| 204.238.166.0/24 | 256 | ARIN | US | 22nd May 1995 |
| 204.238.167.0/24 | 256 | ARIN | US | 22nd May 1995 |
| 204.238.169.0/24 | 256 | ARIN | US | 22nd May 1995 |
| 204.238.170.0/24 | 256 | ARIN | US | 22nd May 1995 |
| 204.238.171.0/24 | 256 | ARIN | US | 22nd May 1995 |
| 204.238.172.0/24 | 256 | ARIN | US | 22nd May 1995 |
| 204.238.173.0/24 | 256 | ARIN | US | 23rd May 1995 |
| 204.238.174.0/24 | 256 | ARIN | US | 23rd May 1995 |
| 204.238.175.0/24 | 256 | ARIN | US | 23rd May 1995 |
| 204.238.176.0/24 | 256 | ARIN | US | 23rd May 1995 |
| 204.238.178.0/24 | 256 | ARIN | US | 23rd May 1995 |
| 204.238.179.0/24 | 256 | ARIN | US | 23rd May 1995 |
| 204.238.18.0/24 | 256 | ARIN | US | 13th Feb 1995 |
| 204.238.180.0/24 | 256 | ARIN | US | 23rd May 1995 |
| 204.238.182.0/24 | 256 | ARIN | US | 23rd May 1995 |
| 204.238.183.0/24 | 256 | ARIN | US | 23rd May 1995 |
| 204.238.184.0/24 | 256 | ARIN | US | 23rd May 1995 |
| 204.238.185.0/24 | 256 | ARIN | US | 23rd May 1995 |
| 204.238.186.0/24 | 256 | ARIN | US | 23rd May 1995 |
| 204.238.188.0/24 | 256 | ARIN | US | 24th May 1995 |
| 204.238.190.0/24 | 256 | ARIN | US | 26th May 1995 |
| 204.238.191.0/24 | 256 | ARIN | US | 26th May 1995 |
| 204.238.192.0/24 | 256 | ARIN | US | 30th May 1995 |
| 204.238.194.0/24 | 256 | ARIN | US | 30th May 1995 |
| 204.238.195.0/24 | 256 | ARIN | US | 30th May 1995 |
| 204.238.196.0/24 | 256 | ARIN | US | 31st May 1995 |
| 204.238.2.0/24 | 256 | ARIN | US | 9th Feb 1995 |
| 204.238.20.0/24 | 256 | ARIN | US | 13th Feb 1995 |
| 204.238.200.0/24 | 256 | ARIN | US | 31st May 1995 |
| 204.238.201.0/24 | 256 | ARIN | US | 31st May 1995 |
| 204.238.202.0/24 | 256 | ARIN | US | 31st May 1995 |
| 204.238.203.0/24 | 256 | ARIN | US | 31st May 1995 |
| 204.238.204.0/24 | 256 | ARIN | US | 31st May 1995 |
| 204.238.205.0/24 | 256 | ARIN | US | 31st May 1995 |
| 204.238.206.0/24 | 256 | ARIN | US | 31st May 1995 |
| 204.238.208.0/24 | 256 | ARIN | US | 1st Jun 1995 |
| 204.238.21.0/24 | 256 | ARIN | US | 4th Mar 1995 |
| 204.238.210.0/24 | 256 | ARIN | US | 2nd Jun 1995 |