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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
26,283 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 192.131.112.0/21 | 2k | ARIN |  US | 23rd Jan 1992 |
| 192.131.12.0/24 | 256 | ARIN | US | 30th Oct 1991 |
| 192.131.120.0/24 | 256 | ARIN | US | 23rd Jan 1992 |
| 192.131.121.0/24 | 256 | ARIN | US | 30th Oct 1991 |
| 192.131.122.0/24 | 256 | ARIN | US | 30th Oct 1991 |
| 192.131.126.0/24 | 256 | ARIN | US | 28th Oct 1991 |
| 192.131.127.0/24 | 256 | ARIN | US | 28th Oct 1991 |
| 192.131.128.0/24 | 256 | ARIN | US | 22nd Jan 1996 |
| 192.131.130.0/24 | 256 | ARIN | US | 28th Oct 1991 |
| 192.131.131.0/24 | 256 | ARIN | US | 28th Oct 1991 |
| 192.131.135.0/24 | 256 | ARIN | US | 30th Oct 1991 |
| 192.131.14.0/24 | 256 | ARIN | US | 30th Oct 1991 |
| 192.131.143.0/24 | 256 | ARIN | US | 30th Oct 1991 |
| 192.131.144.0/24 | 256 | ARIN | US | 30th Oct 1991 |
| 192.131.146.0/24 | 256 | ARIN | US | 28th Apr 1992 |
| 192.131.148.0/24 | 256 | ARIN | US | 26th Nov 1991 |
| 192.131.151.0/24 | 256 | ARIN | US | 26th Nov 1991 |
| 192.131.156.0/22 | 1k | ARIN | US | 28th Apr 1992 |
| 192.131.160.0/20 | 4.1k | ARIN | US | 28th Apr 1992 |
| 192.131.176.0/22 | 1k | ARIN | US | 28th Apr 1992 |
| 192.131.180.0/23 | 512 | ARIN | US | 28th Apr 1992 |
| 192.131.186.0/23 | 512 | ARIN | US | 28th Apr 1992 |
| 192.131.2.0/24 | 256 | ARIN | US | 30th Oct 1991 |
| 192.131.224.0/24 | 256 | ARIN | US | 28th Apr 1992 |
| 192.131.225.0/24 | 256 | ARIN | US | 28th Apr 1992 |
| 192.131.226.0/23 | 512 | ARIN | US | 28th Apr 1992 |
| 192.131.228.0/22 | 1k | ARIN | US | 28th Apr 1992 |
| 192.131.23.0/24 | 256 | ARIN | US | 30th Oct 1991 |
| 192.131.235.0/24 | 256 | ARIN | US | 29th Mar 1992 |
| 192.131.236.0/24 | 256 | ARIN | US | 29th Mar 1992 |
| 192.131.237.0/24 | 256 | ARIN | US | 29th Mar 1992 |
| 192.131.238.0/24 | 256 | ARIN | US | 29th Mar 1992 |
| 192.131.239.0/24 | 256 | ARIN | US | 30th Oct 1991 |
| 192.131.24.0/24 | 256 | ARIN | US | 30th Oct 1991 |
| 192.131.240.0/24 | 256 | ARIN | US | 13th May 1992 |
| 192.131.241.0/24 | 256 | ARIN | US | 29th Mar 1992 |
| 192.131.242.0/24 | 256 | ARIN | US | 29th Mar 1992 |
| 192.131.243.0/24 | 256 | ARIN | US | 31st Oct 1991 |
| 192.131.244.0/24 | 256 | ARIN | US | 31st Oct 1991 |
| 192.131.245.0/24 | 256 | ARIN | US | 31st Oct 1991 |
| 192.131.246.0/24 | 256 | ARIN | US | 31st Oct 1991 |
| 192.131.248.0/24 | 256 | ARIN | US | 14th Feb 1992 |
| 192.131.250.0/24 | 256 | ARIN | US | 31st Oct 1991 |
| 192.131.253.0/24 | 256 | ARIN | US | 31st Oct 1991 |
| 192.131.3.0/24 | 256 | ARIN | US | 30th Oct 1991 |
| 192.131.31.0/24 | 256 | ARIN | US | 30th Oct 1991 |
| 192.131.4.0/23 | 512 | ARIN | US | 4th Feb 2015 |
| 192.131.45.0/24 | 256 | ARIN | US | 13th May 1992 |
| 192.131.46.0/23 | 512 | ARIN | US | 13th May 1992 |
| 192.131.6.0/24 | 256 | ARIN | US | 30th Oct 1991 |