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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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 the most unannounced blocks, largest first.
Unannounced blocks
85,001 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 153.55.0.0/17 | 32.8k | ARIN |  US | 23rd Sept 1991 |
| 153.55.176.0/20 | 4.1k | RIPE NCC |  BZ | 23rd Sept 1991 |
| 153.55.192.0/18 | 16.4k | ARIN | US | 23rd Sept 1991 |
| 153.56.0.0/17 | 32.8k | RIPE NCC |  AE | 23rd Sept 1991 |
| 153.56.144.0/24 | 256 | RIPE NCC |  AZ | 23rd Sept 1991 |
| 153.56.145.0/24 | 256 | RIPE NCC | AE | 23rd Sept 1991 |
| 153.56.146.0/23 | 512 | RIPE NCC | AE | 23rd Sept 1991 |
| 153.56.148.0/24 | 256 | RIPE NCC | AE | 23rd Sept 1991 |
| 153.56.152.0/23 | 512 | RIPE NCC | AE | 23rd Sept 1991 |
| 153.56.173.0/24 | 256 | RIPE NCC |  SA | 23rd Sept 1991 |
| 153.56.174.0/23 | 512 | RIPE NCC | SA | 23rd Sept 1991 |
| 153.56.185.0/24 | 256 | RIPE NCC |  TR | 23rd Sept 1991 |
| 153.56.186.0/23 | 512 | RIPE NCC | TR | 23rd Sept 1991 |
| 153.56.190.0/23 | 512 | RIPE NCC | TR | 23rd Sept 1991 |
| 153.56.192.0/21 | 2k | RIPE NCC |  AT | 23rd Sept 1991 |
| 153.56.224.0/19 | 8.2k | RIPE NCC | AE | 23rd Sept 1991 |
| 153.57.224.0/19 | 8.2k | ARIN | US | 10th Apr 2026 |
| 153.58.0.0/16 | 65.5k | ARIN | US | 23rd Sept 1991 |
| 153.59.0.0/16 | 65.5k | RIPE NCC |  FR | 23rd Sept 1991 |
| 153.60.192.0/18 | 16.4k | RIPE NCC |  DE | 23rd Sept 1991 |
| 153.60.32.0/19 | 8.2k | RIPE NCC | DE | 23rd Sept 1991 |
| 153.60.64.0/18 | 16.4k | ARIN | US | 6th Apr 2026 |
| 153.62.0.0/16 | 65.5k | ARIN | US | 23rd Sept 1991 |
| 153.63.0.0/16 | 65.5k | ARIN | US | 23rd Sept 1991 |
| 153.70.0.0/15 | 131k | ARIN | US | 23rd Sept 1991 |
| 153.73.0.0/16 | 65.5k | ARIN | US | 23rd Sept 1991 |
| 153.74.0.0/16 | 65.5k | ARIN | US | 23rd Sept 1991 |
| 153.75.112.0/20 | 4.1k | ARIN | US | 6th May 2026 |
| 153.75.128.0/19 | 8.2k | RIPE NCC |  CH | 23rd Sept 1991 |
| 153.75.16.0/20 | 4.1k | ARIN | US | 24th Apr 2026 |
| 153.75.160.0/19 | 8.2k | ARIN | US | 23rd Sept 1991 |
| 153.75.96.0/20 | 4.1k | ARIN | US | 21st May 2026 |
| 153.76.128.0/19 | 8.2k | ARIN | US | 23rd Sept 1991 |
| 153.76.160.0/20 | 4.1k | RIPE NCC |  RU | 23rd Sept 1991 |
| 153.76.176.0/23 | 512 | RIPE NCC |  CZ | 23rd Sept 1991 |
| 153.76.180.0/22 | 1k | RIPE NCC | CZ | 23rd Sept 1991 |
| 153.76.184.0/21 | 2k | RIPE NCC | CZ | 23rd Sept 1991 |
| 153.76.224.0/21 | 2k | RIPE NCC | DE | 23rd Sept 1991 |
| 153.76.232.0/21 | 2k | RIPE NCC |  MY | 23rd Sept 1991 |
| 153.76.240.0/22 | 1k | APNIC |  ID | 23rd Sept 1991 |
| 153.76.244.0/22 | 1k | ARIN | US | 23rd Sept 1991 |
| 153.76.252.0/22 | 1k | RIPE NCC | DE | 23rd Sept 1991 |
| 153.76.32.0/19 | 8.2k | RIPE NCC | DE | 23rd Sept 1991 |
| 153.78.0.0/16 | 65.5k | ARIN | US | 23rd Sept 1991 |
| 153.79.0.0/18 | 16.4k | ARIN | US | 23rd Sept 1991 |
| 153.79.128.0/19 | 8.2k | RIPE NCC | US | 23rd Sept 1991 |
| 153.79.160.0/21 | 2k | ARIN | US | 23rd Sept 1991 |
| 153.79.168.0/21 | 2k | RIPE NCC |  GB | 23rd Sept 1991 |
| 153.79.176.0/22 | 1k | RIPE NCC |  HK | 23rd Sept 1991 |
| 153.79.180.0/22 | 1k | RIPE NCC | RU | 23rd Sept 1991 |