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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
26,993 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 155.35.16.0/20 | 4.1k | ARIN |  US | 4th Feb 1992 |
| 155.35.192.0/19 | 8.2k | ARIN | US | 4th Feb 1992 |
| 155.35.2.0/23 | 512 | ARIN | US | 4th Feb 1992 |
| 155.35.224.0/23 | 512 | ARIN | US | 4th Feb 1992 |
| 155.35.227.0/24 | 256 | ARIN | US | 4th Feb 1992 |
| 155.35.228.0/22 | 1k | ARIN | US | 4th Feb 1992 |
| 155.35.233.0/24 | 256 | ARIN | US | 4th Feb 1992 |
| 155.35.234.0/23 | 512 | ARIN | US | 4th Feb 1992 |
| 155.35.236.0/22 | 1k | ARIN | US | 4th Feb 1992 |
| 155.35.240.0/20 | 4.1k | ARIN | US | 4th Feb 1992 |
| 155.35.32.0/23 | 512 | ARIN | US | 4th Feb 1992 |
| 155.35.36.0/22 | 1k | ARIN | US | 4th Feb 1992 |
| 155.35.4.0/22 | 1k | ARIN | US | 4th Feb 1992 |
| 155.35.40.0/22 | 1k | ARIN | US | 4th Feb 1992 |
| 155.35.44.0/23 | 512 | ARIN | US | 4th Feb 1992 |
| 155.35.48.0/20 | 4.1k | ARIN | US | 4th Feb 1992 |
| 155.35.64.0/18 | 16.4k | ARIN | US | 4th Feb 1992 |
| 155.35.8.0/21 | 2k | ARIN | US | 4th Feb 1992 |
| 155.36.0.0/16 | 65.5k | ARIN | US | 8th Apr 1992 |
| 155.46.64.0/19 | 8.2k | ARIN | US | 26th Aug 1994 |
| 155.46.96.0/19 | 8.2k | ARIN | US | 26th Aug 1994 |
| 155.51.0.0/16 | 65.5k | ARIN | US | 23rd Mar 1992 |
| 155.61.0.0/16 | 65.5k | ARIN | US | 30th Oct 1991 |
| 155.67.0.0/16 | 65.5k | ARIN | US | 31st Oct 1991 |
| 155.68.0.0/16 | 65.5k | ARIN | US | 30th Oct 1991 |
| 155.90.0.0/16 | 65.5k | ARIN | US | 31st Oct 1991 |
| 155.94.234.0/24 | 256 | ARIN | US | 11th Jun 2014 |
| 155.94.80.0/20 | 4.1k | ARIN | US | 13th Oct 2022 |
| 155.96.0.0/16 | 65.5k | ARIN | US | 13th Nov 1991 |
| 156.100.0.0/16 | 65.5k | ARIN | US | 24th Dec 1991 |
| 156.102.0.0/16 | 65.5k | ARIN | US | 24th Dec 1991 |
| 156.103.0.0/16 | 65.5k | ARIN | US | 24th Dec 1991 |
| 156.104.0.0/16 | 65.5k | ARIN | US | 24th Dec 1991 |
| 156.105.0.0/16 | 65.5k | ARIN | US | 24th Dec 1991 |
| 156.117.0.0/16 | 65.5k | ARIN | US | 8th Jan 1992 |
| 156.119.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.120.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.121.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.122.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.123.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.124.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.125.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.126.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.127.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.128.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.129.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.130.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.131.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.132.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |
| 156.136.0.0/16 | 65.5k | ARIN | US | 25th Mar 1992 |