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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
26,315 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 199.38.156.0/24 | 256 | ARIN |  US | 12th Nov 1993 |
| 199.38.157.0/24 | 256 | ARIN | US | 12th Nov 1993 |
| 199.38.16.0/21 | 2k | ARIN | US | 28th Oct 1993 |
| 199.38.176.0/22 | 1k | ARIN | US | 14th Nov 2011 |
| 199.38.224.0/21 | 2k | ARIN | US | 3rd Sept 2024 |
| 199.38.24.0/24 | 256 | ARIN | US | 28th Oct 1993 |
| 199.38.251.0/24 | 256 | ARIN | US | 3rd Oct 2025 |
| 199.38.8.0/21 | 2k | ARIN | US | 1st Nov 1993 |
| 199.38.88.0/21 | 2k | ARIN | US | 7th Nov 2011 |
| 199.39.0.0/16 | 65.5k | ARIN | US | 28th Oct 1993 |
| 199.4.0.0/21 | 2k | ARIN | US | 14th Sept 1993 |
| 199.4.128.0/24 | 256 | ARIN | US | 3rd Dec 1993 |
| 199.4.129.0/24 | 256 | ARIN | US | 6th Dec 1993 |
| 199.4.132.0/24 | 256 | ARIN | US | 6th Dec 1993 |
| 199.4.136.0/24 | 256 | ARIN | US | 6th Dec 1993 |
| 199.4.139.0/24 | 256 | ARIN | US | 6th Dec 1993 |
| 199.4.145.0/24 | 256 | ARIN | US | 6th Dec 1993 |
| 199.4.148.0/24 | 256 | ARIN | US | 6th Dec 1993 |
| 199.4.149.0/24 | 256 | ARIN | US | 7th Dec 1993 |
| 199.4.153.0/24 | 256 | ARIN | US | 7th Dec 1993 |
| 199.4.154.0/23 | 512 | ARIN | US | 7th Dec 1993 |
| 199.4.156.0/24 | 256 | ARIN | US | 7th Dec 1993 |
| 199.4.157.0/24 | 256 | ARIN | US | 7th Dec 1993 |
| 199.4.159.0/24 | 256 | ARIN | US | 7th Dec 1993 |
| 199.4.160.0/24 | 256 | ARIN | US | 7th Dec 1993 |
| 199.4.161.0/24 | 256 | ARIN | US | 18th Aug 2015 |
| 199.4.168.0/21 | 2k | ARIN | US | 7th Dec 1993 |
| 199.4.176.0/22 | 1k | ARIN | US | 7th Dec 1993 |
| 199.4.180.0/22 | 1k | ARIN | US | 8th Dec 1993 |
| 199.4.184.0/24 | 256 | ARIN | US | 8th Dec 1993 |
| 199.4.185.0/24 | 256 | ARIN | US | 8th Dec 1993 |
| 199.4.186.0/24 | 256 | ARIN | US | 8th Dec 1993 |
| 199.4.187.0/24 | 256 | ARIN | US | 8th Dec 1993 |
| 199.4.188.0/24 | 256 | ARIN | US | 8th Dec 1993 |
| 199.4.193.0/24 | 256 | ARIN | US | 8th Dec 1993 |
| 199.4.194.0/24 | 256 | ARIN | US | 8th Dec 1993 |
| 199.4.196.0/24 | 256 | ARIN | US | 8th Dec 1993 |
| 199.4.197.0/24 | 256 | ARIN | US | 8th Dec 1993 |
| 199.4.198.0/24 | 256 | ARIN | US | 8th Dec 1993 |
| 199.4.199.0/24 | 256 | ARIN | US | 9th Dec 1993 |
| 199.4.200.0/22 | 1k | ARIN | US | 9th Dec 1993 |
| 199.4.204.0/24 | 256 | ARIN | US | 9th Dec 1993 |
| 199.4.206.0/24 | 256 | ARIN | US | 9th Dec 1993 |
| 199.4.207.0/24 | 256 | ARIN | US | 9th Dec 1993 |
| 199.4.208.0/24 | 256 | ARIN | US | 9th Dec 1993 |
| 199.4.209.0/24 | 256 | ARIN | US | 9th Dec 1993 |
| 199.4.210.0/24 | 256 | ARIN | US | 9th Dec 1993 |
| 199.4.214.0/24 | 256 | ARIN | US | 10th Dec 1993 |
| 199.4.215.0/24 | 256 | ARIN | US | 10th Dec 1993 |
| 199.4.219.0/24 | 256 | ARIN | US | 10th Dec 1993 |