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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
26,277 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 155.16.0.0/16 | 65.5k | ARIN |  US | 30th Oct 1991 |
| 155.162.0.0/16 | 65.5k | ARIN | US | 24th Mar 1992 |
| 155.164.0.0/16 | 65.5k | ARIN | US | 24th Mar 1992 |
| 155.167.0.0/16 | 65.5k | ARIN | US | 24th Mar 1992 |
| 155.168.0.0/16 | 65.5k | ARIN | US | 24th Mar 1992 |
| 155.169.0.0/16 | 65.5k | ARIN | US | 24th Mar 1992 |
| 155.17.0.0/16 | 65.5k | ARIN | US | 30th Oct 1991 |
| 155.171.0.0/16 | 65.5k | ARIN | US | 24th Mar 1992 |
| 155.172.0.0/16 | 65.5k | ARIN | US | 24th Mar 1992 |
| 155.173.0.0/16 | 65.5k | ARIN | US | 24th Mar 1992 |
| 155.174.0.0/16 | 65.5k | ARIN | US | 24th Mar 1992 |
| 155.175.0.0/16 | 65.5k | ARIN | US | 24th Mar 1992 |
| 155.176.0.0/16 | 65.5k | ARIN | US | 24th Mar 1992 |
| 155.177.0.0/16 | 65.5k | ARIN | US | 15th Nov 1991 |
| 155.179.0.0/16 | 65.5k | ARIN | US | 23rd Mar 1992 |
| 155.180.0.0/16 | 65.5k | ARIN | US | 18th Nov 1991 |
| 155.182.0.0/16 | 65.5k | ARIN | US | 18th Nov 1991 |
| 155.189.0.0/16 | 65.5k | ARIN | US | 4th Oct 1993 |
| 155.191.0.0/16 | 65.5k | ARIN | US | 22nd Nov 1991 |
| 155.195.0.0/16 | 65.5k | ARIN | US | 22nd Nov 1991 |
| 155.200.0.0/16 | 65.5k | ARIN | US | 30th Oct 1991 |
| 155.208.0.0/16 | 65.5k | ARIN | US | 19th Aug 1996 |
| 155.224.0.0/16 | 65.5k | ARIN | US | 14th Feb 1992 |
| 155.241.0.0/16 | 65.5k | ARIN | US | 9th Dec 1991 |
| 155.242.0.0/16 | 65.5k | ARIN | US | 9th Dec 1991 |
| 155.243.0.0/16 | 65.5k | ARIN | US | 9th Dec 1991 |
| 155.244.0.0/16 | 65.5k | ARIN | US | 11th Dec 1991 |
| 155.254.1.0/24 | 256 | ARIN | US | 11th Dec 1991 |
| 155.254.128.0/23 | 512 | ARIN | US | 11th Dec 1991 |
| 155.254.130.0/24 | 256 | ARIN | US | 11th Dec 1991 |
| 155.254.131.0/24 | 256 | ARIN | US | 11th Sept 2015 |
| 155.254.216.0/22 | 1k | ARIN | US | 8th Jan 2021 |
| 155.254.232.0/22 | 1k | ARIN | US | 11th Jan 2021 |
| 155.34.0.0/16 | 65.5k | ARIN | US | 23rd Mar 1992 |
| 155.35.0.0/24 | 256 | ARIN | US | 4th Feb 1992 |
| 155.35.128.0/18 | 16.4k | ARIN | US | 4th Feb 1992 |
| 155.35.16.0/20 | 4.1k | ARIN | US | 4th Feb 1992 |
| 155.35.192.0/19 | 8.2k | ARIN | US | 4th Feb 1992 |
| 155.35.2.0/23 | 512 | ARIN | US | 4th Feb 1992 |
| 155.35.224.0/23 | 512 | ARIN | US | 4th Feb 1992 |
| 155.35.227.0/24 | 256 | ARIN | US | 4th Feb 1992 |
| 155.35.228.0/22 | 1k | ARIN | US | 4th Feb 1992 |
| 155.35.233.0/24 | 256 | ARIN | US | 4th Feb 1992 |
| 155.35.234.0/23 | 512 | ARIN | US | 4th Feb 1992 |
| 155.35.236.0/22 | 1k | ARIN | US | 4th Feb 1992 |
| 155.35.240.0/20 | 4.1k | ARIN | US | 4th Feb 1992 |
| 155.35.32.0/23 | 512 | ARIN | US | 4th Feb 1992 |
| 155.35.36.0/22 | 1k | ARIN | US | 4th Feb 1992 |
| 155.35.4.0/22 | 1k | ARIN | US | 4th Feb 1992 |
| 155.35.40.0/22 | 1k | ARIN | US | 4th Feb 1992 |