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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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 |
|---|---|---|---|---|
| 150.247.96.0/19 | 8.2k | ARIN |  US | 5th Aug 1991 |
| 150.252.112.0/20 | 4.1k | ARIN | US | 19th Aug 1991 |
| 150.40.72.0/21 | 2k | ARIN | US | 26th Jun 2024 |
| 150.40.80.0/20 | 4.1k | ARIN | US | 26th Jun 2024 |
| 151.108.0.0/16 | 65.5k | ARIN | US | 30th May 1991 |
| 151.109.0.0/16 | 65.5k | ARIN | US | 16th May 1991 |
| 151.116.0.0/15 | 131k | ARIN | US | 11th Jun 1991 |
| 151.118.0.0/16 | 65.5k | ARIN | US | 11th Jun 1991 |
| 151.119.0.0/16 | 65.5k | ARIN | US | 11th Jun 1991 |
| 151.126.0.0/16 | 65.5k | ARIN | US | 17th Jun 1991 |
| 151.128.0.0/16 | 65.5k | ARIN | US | 17th Jun 1991 |
| 151.148.16.0/20 | 4.1k | ARIN | US | 19th Sept 2022 |
| 151.148.8.0/21 | 2k | ARIN | US | 19th Sept 2022 |
| 151.167.0.0/16 | 65.5k | ARIN | US | 7th Aug 1991 |
| 151.171.0.0/16 | 65.5k | ARIN | US | 5th Sept 1991 |
| 151.174.0.0/16 | 65.5k | ARIN | US | 5th Sept 1991 |
| 151.181.128.0/19 | 8.2k | ARIN | US | 17th Sept 1991 |
| 151.181.176.0/20 | 4.1k | ARIN | US | 17th Sept 1991 |
| 151.209.0.0/16 | 65.5k | ARIN | US | 25th Sept 1991 |
| 151.210.64.0/19 | 8.2k | ARIN | US | 31st Jul 2026 |
| 152.100.0.0/16 | 65.5k | ARIN | US | 12th Sept 1991 |
| 152.116.0.0/16 | 65.5k | ARIN | US | 13th Aug 1991 |
| 152.117.24.0/21 | 2k | ARIN | US | 30th Sept 2026 |
| 152.117.32.0/20 | 4.1k | ARIN | US | 13th Aug 1991 |
| 152.140.0.0/15 | 131k | ARIN | US | 22nd Aug 1991 |
| 152.142.0.0/16 | 65.5k | ARIN | US | 22nd Aug 1991 |
| 152.144.0.0/16 | 65.5k | ARIN | US | 22nd Aug 1991 |
| 152.146.0.0/16 | 65.5k | ARIN | US | 23rd Aug 1991 |
| 152.159.0.0/16 | 65.5k | ARIN | US | 18th Mar 1992 |
| 152.161.0.0/16 | 65.5k | ARIN | US | 1st Apr 1992 |
| 152.162.0.0/16 | 65.5k | ARIN | US | 1st Apr 1992 |
| 152.224.0.0/15 | 131k | ARIN | US | 23rd Sept 1991 |
| 152.235.0.0/17 | 32.8k | ARIN | US | 9th Feb 2026 |
| 152.35.0.0/16 | 65.5k | ARIN | US | 10th Jan 1992 |
| 152.36.32.0/19 | 8.2k | ARIN | US | 10th Jan 1992 |
| 152.55.252.0/22 | 1k | ARIN | US | 28th Apr 2026 |
| 152.64.0.0/16 | 65.5k | ARIN | US | 19th Aug 1991 |
| 153.14.0.0/16 | 65.5k | ARIN | US | 16th Sept 1991 |
| 153.15.0.0/16 | 65.5k | RIPE NCC | US | 1st Sept 1993 |
| 153.16.0.0/16 | 65.5k | ARIN | US | 17th Sept 1991 |
| 153.30.0.0/16 | 65.5k | ARIN | US | 23rd Sept 1991 |
| 153.40.0.0/16 | 65.5k | ARIN | US | 3rd Jan 1992 |
| 153.50.0.0/16 | 65.5k | ARIN | US | 10th Jun 1992 |
| 153.55.0.0/17 | 32.8k | ARIN | US | 23rd Sept 1991 |
| 153.55.192.0/18 | 16.4k | ARIN | US | 23rd Sept 1991 |
| 153.57.224.0/19 | 8.2k | ARIN | US | 10th Apr 2026 |
| 153.60.64.0/18 | 16.4k | ARIN | US | 6th Apr 2026 |
| 153.62.0.0/16 | 65.5k | ARIN | US | 23rd Sept 1991 |
| 153.70.0.0/15 | 131k | ARIN | US | 23rd Sept 1991 |
| 153.73.0.0/16 | 65.5k | ARIN | US | 23rd Sept 1991 |