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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
26,300 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 198.137.172.0/24 | 256 | ARIN |  US | 11th May 1993 |
| 198.137.173.0/24 | 256 | ARIN | US | 12th May 1993 |
| 198.137.174.0/24 | 256 | ARIN | US | 14th Sept 2022 |
| 198.137.175.0/24 | 256 | ARIN | US | 12th May 1993 |
| 198.137.176.0/22 | 1k | ARIN | US | 12th May 1993 |
| 198.137.180.0/24 | 256 | ARIN | US | 13th May 1993 |
| 198.137.181.0/24 | 256 | ARIN | US | 13th May 1993 |
| 198.137.182.0/23 | 512 | ARIN | US | 13th May 1993 |
| 198.137.184.0/23 | 512 | ARIN | US | 18th Apr 2013 |
| 198.137.186.0/24 | 256 | ARIN | US | 13th May 1993 |
| 198.137.187.0/24 | 256 | ARIN | US | 13th May 1993 |
| 198.137.188.0/24 | 256 | ARIN | US | 17th May 1993 |
| 198.137.192.0/24 | 256 | ARIN | US | 17th May 1993 |
| 198.137.193.0/24 | 256 | ARIN | US | 17th May 1993 |
| 198.137.195.0/24 | 256 | ARIN | US | 17th May 1993 |
| 198.137.196.0/24 | 256 | ARIN | US | 17th May 1993 |
| 198.137.197.0/24 | 256 | ARIN | US | 17th May 1993 |
| 198.137.198.0/24 | 256 | ARIN | US | 17th May 1993 |
| 198.137.200.0/24 | 256 | ARIN | US | 17th May 1993 |
| 198.137.204.0/24 | 256 | ARIN | US | 19th May 1993 |
| 198.137.206.0/24 | 256 | ARIN | US | 19th May 1993 |
| 198.137.207.0/24 | 256 | ARIN | US | 19th May 1993 |
| 198.137.208.0/24 | 256 | ARIN | US | 19th May 1993 |
| 198.137.209.0/24 | 256 | ARIN | US | 19th May 1993 |
| 198.137.210.0/24 | 256 | ARIN | US | 19th May 1993 |
| 198.137.211.0/24 | 256 | ARIN | US | 19th May 1993 |
| 198.137.212.0/24 | 256 | ARIN | US | 19th May 1993 |
| 198.137.213.0/24 | 256 | ARIN | US | 19th May 1993 |
| 198.137.216.0/24 | 256 | ARIN | US | 19th May 1993 |
| 198.137.217.0/24 | 256 | ARIN | US | 19th May 1993 |
| 198.137.218.0/24 | 256 | ARIN | US | 19th May 1993 |
| 198.137.219.0/24 | 256 | ARIN | US | 13th Jun 2013 |
| 198.137.220.0/24 | 256 | ARIN | US | 19th May 1993 |
| 198.137.221.0/24 | 256 | ARIN | US | 19th May 1993 |
| 198.137.222.0/24 | 256 | ARIN | US | 19th May 1993 |
| 198.137.223.0/24 | 256 | ARIN | US | 19th May 1993 |
| 198.137.228.0/24 | 256 | ARIN | US | 20th May 1993 |
| 198.137.230.0/24 | 256 | ARIN | US | 20th May 1993 |
| 198.137.231.0/24 | 256 | ARIN | US | 30th May 2025 |
| 198.137.236.0/24 | 256 | ARIN | US | 21st May 1993 |
| 198.137.237.0/24 | 256 | ARIN | US | 21st May 1993 |
| 198.137.242.0/24 | 256 | ARIN | US | 24th May 1993 |
| 198.137.243.0/24 | 256 | ARIN | US | 24th May 1993 |
| 198.137.244.0/24 | 256 | ARIN | US | 24th May 1993 |
| 198.137.245.0/24 | 256 | ARIN | US | 24th May 1993 |
| 198.137.246.0/23 | 512 | ARIN | US | 25th Apr 2013 |
| 198.137.248.0/24 | 256 | ARIN | US | 1st Jul 2022 |
| 198.137.249.0/24 | 256 | ARIN | US | 25th May 1993 |
| 198.137.250.0/24 | 256 | ARIN | US | 25th May 1993 |
| 198.137.251.0/24 | 256 | ARIN | US | 25th May 1993 |