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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
Browse by country
Countries with the most unannounced blocks, largest first.
Unannounced blocks in United States
26,963 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 143.203.120.0/22 | 1k | ARIN |  US | 2nd Oct 2026 |
| 143.203.128.0/22 | 1k | ARIN | US | 2nd Oct 2026 |
| 143.203.136.0/22 | 1k | ARIN | US | 2nd Oct 2026 |
| 143.203.148.0/22 | 1k | ARIN | US | 12th Oct 2026 |
| 143.203.156.0/22 | 1k | ARIN | US | 2nd Oct 2026 |
| 143.203.16.0/22 | 1k | ARIN | US | 2nd Oct 2026 |
| 143.203.160.0/22 | 1k | ARIN | US | 2nd Oct 2026 |
| 143.203.168.0/22 | 1k | ARIN | US | 2nd Oct 2026 |
| 143.203.172.0/22 | 1k | ARIN | US | 2nd Oct 2026 |
| 143.203.192.0/22 | 1k | ARIN | US | 2nd Oct 2026 |
| 143.203.196.0/22 | 1k | ARIN | US | 2nd Oct 2026 |
| 143.203.204.0/22 | 1k | ARIN | US | 2nd Oct 2026 |
| 143.203.212.0/22 | 1k | ARIN | US | 2nd Oct 2026 |
| 143.203.236.0/22 | 1k | ARIN | US | 5th Oct 2026 |
| 143.203.24.0/22 | 1k | ARIN | US | 2nd Oct 2026 |
| 143.203.240.0/22 | 1k | ARIN | US | 5th Oct 2026 |
| 143.203.248.0/22 | 1k | ARIN | US | 5th Oct 2026 |
| 143.203.252.0/22 | 1k | ARIN | US | 1st Oct 2026 |
| 143.203.28.0/22 | 1k | ARIN | US | 2nd Oct 2026 |
| 143.203.4.0/22 | 1k | ARIN | US | 6th Oct 2026 |
| 143.203.60.0/22 | 1k | ARIN | US | 2nd Oct 2026 |
| 143.203.64.0/22 | 1k | ARIN | US | 2nd Oct 2026 |
| 143.203.68.0/22 | 1k | ARIN | US | 26th Oct 2026 |
| 143.203.80.0/22 | 1k | ARIN | US | 2nd Oct 2026 |
| 143.203.84.0/22 | 1k | ARIN | US | 2nd Oct 2026 |
| 143.203.88.0/22 | 1k | ARIN | US | 26th Oct 2026 |
| 143.203.92.0/22 | 1k | ARIN | US | 6th Oct 2026 |
| 143.219.0.0/16 | 65.5k | ARIN | US | 30th Jun 1990 |
| 143.222.0.0/16 | 65.5k | ARIN | US | 30th Jun 1990 |
| 143.223.101.0/24 | 256 | ARIN | US | 30th Jun 1990 |
| 143.223.136.0/24 | 256 | ARIN | US | 30th Jun 1990 |
| 143.223.140.0/23 | 512 | ARIN | US | 30th Jun 1990 |
| 143.223.16.0/23 | 512 | ARIN | US | 18th Feb 2026 |
| 143.223.160.0/24 | 256 | ARIN | US | 20th Feb 2026 |
| 143.223.161.0/24 | 256 | ARIN | US | 30th Jun 1990 |
| 143.223.164.0/22 | 1k | ARIN | US | 30th Jun 1990 |
| 143.223.173.0/24 | 256 | ARIN | US | 30th Jun 1990 |
| 143.223.175.0/24 | 256 | ARIN | US | 30th Jun 1990 |
| 143.223.180.0/22 | 1k | ARIN | US | 30th Jun 1990 |
| 143.223.20.0/22 | 1k | ARIN | US | 30th Jun 1990 |
| 143.242.0.0/16 | 65.5k | ARIN | US | 23rd Oct 1990 |
| 143.243.0.0/16 | 65.5k | ARIN | US | 23rd Oct 1990 |
| 143.246.44.0/22 | 1k | APNIC | US | 26th Oct 1990 |
| 143.246.64.0/18 | 16.4k | ARIN | US | 24th Aug 2026 |
| 143.247.0.0/16 | 65.5k | ARIN | US | 26th Oct 1990 |
| 143.251.0.0/16 | 65.5k | ARIN | US | 26th Oct 1990 |
| 143.55.154.0/24 | 256 | ARIN | US | 15th May 2020 |
| 143.63.0.0/16 | 65.5k | ARIN | US | 26th Mar 1990 |
| 143.82.0.0/16 | 65.5k | ARIN | US | 26th Mar 1990 |
| 143.91.0.0/16 | 65.5k | ARIN | US | 7th Sept 1990 |