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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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 in United States
27,034 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 199.164.243.0/24 | 256 | ARIN |  US | 22nd Mar 1994 |
| 199.164.244.0/24 | 256 | ARIN | US | 22nd Mar 1994 |
| 199.164.245.0/24 | 256 | ARIN | US | 22nd Mar 1994 |
| 199.164.246.0/24 | 256 | ARIN | US | 22nd Mar 1994 |
| 199.164.247.0/24 | 256 | ARIN | US | 3rd Apr 2025 |
| 199.164.248.0/23 | 512 | ARIN | US | 22nd Mar 1994 |
| 199.164.250.0/24 | 256 | ARIN | US | 22nd Mar 1994 |
| 199.164.251.0/24 | 256 | ARIN | US | 22nd Mar 1994 |
| 199.164.252.0/24 | 256 | ARIN | US | 22nd Mar 1994 |
| 199.164.254.0/24 | 256 | ARIN | US | 22nd Mar 1994 |
| 199.165.0.0/21 | 2k | ARIN | US | 2nd Feb 1994 |
| 199.165.128.0/24 | 256 | ARIN | US | 23rd Mar 1994 |
| 199.165.129.0/24 | 256 | ARIN | US | 14th Apr 1997 |
| 199.165.130.0/24 | 256 | ARIN | US | 23rd Mar 1994 |
| 199.165.131.0/24 | 256 | ARIN | US | 23rd Mar 1994 |
| 199.165.132.0/24 | 256 | ARIN | US | 23rd Mar 1994 |
| 199.165.133.0/24 | 256 | ARIN | US | 23rd Mar 1994 |
| 199.165.135.0/24 | 256 | ARIN | US | 23rd Mar 1994 |
| 199.165.139.0/24 | 256 | ARIN | US | 2nd Jul 2026 |
| 199.165.140.0/24 | 256 | ARIN | US | 23rd Mar 1994 |
| 199.165.141.0/24 | 256 | ARIN | US | 2nd Oct 2018 |
| 199.165.142.0/24 | 256 | ARIN | US | 23rd Mar 1994 |
| 199.165.144.0/24 | 256 | ARIN | US | 23rd Mar 1994 |
| 199.165.145.0/24 | 256 | ARIN | US | 23rd Mar 1994 |
| 199.165.150.0/24 | 256 | ARIN | US | 23rd Mar 1994 |
| 199.165.151.0/24 | 256 | ARIN | US | 17th Sept 2012 |
| 199.165.156.0/24 | 256 | ARIN | US | 24th Mar 1994 |
| 199.165.157.0/24 | 256 | ARIN | US | 24th Mar 1994 |
| 199.165.160.0/24 | 256 | ARIN | US | 24th Mar 1994 |
| 199.165.161.0/24 | 256 | ARIN | US | 24th Mar 1994 |
| 199.165.164.0/23 | 512 | ARIN | US | 24th Mar 1994 |
| 199.165.166.0/23 | 512 | ARIN | US | 25th Mar 1994 |
| 199.165.168.0/22 | 1k | ARIN | US | 25th Mar 1994 |
| 199.165.172.0/24 | 256 | ARIN | US | 25th Mar 1994 |
| 199.165.173.0/24 | 256 | ARIN | US | 25th Mar 1994 |
| 199.165.174.0/24 | 256 | ARIN | US | 25th Mar 1994 |
| 199.165.175.0/24 | 256 | ARIN | US | 25th Mar 1994 |
| 199.165.176.0/24 | 256 | ARIN | US | 25th Mar 1994 |
| 199.165.178.0/24 | 256 | ARIN | US | 25th Mar 1994 |
| 199.165.181.0/24 | 256 | ARIN | US | 25th Mar 1994 |
| 199.165.182.0/23 | 512 | ARIN | US | 25th Mar 1994 |
| 199.165.184.0/24 | 256 | ARIN | US | 25th Mar 1994 |
| 199.165.185.0/24 | 256 | ARIN | US | 25th Mar 1994 |
| 199.165.186.0/24 | 256 | ARIN | US | 25th Mar 1994 |
| 199.165.187.0/24 | 256 | ARIN | US | 28th Mar 1994 |
| 199.165.188.0/24 | 256 | ARIN | US | 14th Jul 1997 |
| 199.165.189.0/24 | 256 | ARIN | US | 28th Mar 1994 |
| 199.165.190.0/24 | 256 | ARIN | US | 28th Mar 1994 |
| 199.165.191.0/24 | 256 | ARIN | US | 28th Mar 1994 |
| 199.165.192.0/24 | 256 | ARIN | US | 28th Mar 1994 |