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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
27,001 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 192.103.128.0/24 | 256 | ARIN |  US | 31st Jul 1991 |
| 192.103.129.0/24 | 256 | ARIN | US | 31st Jul 1991 |
| 192.103.13.0/24 | 256 | ARIN | US | 28th Jun 1991 |
| 192.103.134.0/24 | 256 | ARIN | US | 9th Aug 1991 |
| 192.103.135.0/24 | 256 | ARIN | US | 12th Aug 1991 |
| 192.103.140.0/24 | 256 | ARIN | US | 12th Aug 1991 |
| 192.103.141.0/24 | 256 | ARIN | US | 12th Aug 1991 |
| 192.103.142.0/24 | 256 | ARIN | US | 13th Aug 1991 |
| 192.103.143.0/24 | 256 | ARIN | US | 13th Aug 1991 |
| 192.103.145.0/24 | 256 | ARIN | US | 13th Aug 1991 |
| 192.103.146.0/24 | 256 | ARIN | US | 14th Aug 1991 |
| 192.103.15.0/24 | 256 | ARIN | US | 1st Jul 1991 |
| 192.103.16.0/24 | 256 | ARIN | US | 1st Jul 1991 |
| 192.103.17.0/24 | 256 | ARIN | US | 1st Jul 1991 |
| 192.103.18.0/24 | 256 | ARIN | US | 1st Jul 1991 |
| 192.103.19.0/24 | 256 | ARIN | US | 1st Jul 1991 |
| 192.103.22.0/24 | 256 | ARIN | US | 5th Jul 1991 |
| 192.103.240.0/21 | 2k | ARIN | US | 14th Aug 1991 |
| 192.103.25.0/24 | 256 | ARIN | US | 5th Jul 1991 |
| 192.103.250.0/24 | 256 | ARIN | US | 15th Jan 2015 |
| 192.103.253.0/24 | 256 | ARIN | US | 23rd Sept 2022 |
| 192.103.3.0/24 | 256 | ARIN | US | 29th Apr 1991 |
| 192.103.47.0/24 | 256 | ARIN | US | 11th Jul 1991 |
| 192.103.48.0/24 | 256 | ARIN | US | 11th Jul 1991 |
| 192.103.49.0/24 | 256 | ARIN | US | 12th Jul 1991 |
| 192.103.5.0/24 | 256 | ARIN | US | 27th Jan 1995 |
| 192.103.54.0/24 | 256 | ARIN | US | 11th Jul 1991 |
| 192.103.55.0/24 | 256 | ARIN | US | 11th Jul 1991 |
| 192.103.57.0/24 | 256 | ARIN | US | 11th Jul 1991 |
| 192.103.58.0/24 | 256 | ARIN | US | 11th Jul 1991 |
| 192.103.59.0/24 | 256 | ARIN | US | 12th Jul 1991 |
| 192.103.6.0/24 | 256 | ARIN | US | 20th Jun 1991 |
| 192.103.60.0/22 | 1k | ARIN | US | 12th Jul 1991 |
| 192.103.79.0/24 | 256 | ARIN | US | 12th Jul 1991 |
| 192.103.8.0/24 | 256 | ARIN | US | 21st Jun 1991 |
| 192.103.81.0/24 | 256 | ARIN | US | 12th Jul 1991 |
| 192.103.82.0/24 | 256 | ARIN | US | 13th Jul 1991 |
| 192.103.83.0/24 | 256 | ARIN | US | 13th Jul 1991 |
| 192.103.9.0/24 | 256 | ARIN | US | 20th Jun 1991 |
| 192.104.104.0/23 | 512 | ARIN | US | 16th May 1991 |
| 192.104.106.0/24 | 256 | ARIN | US | 16th May 1991 |
| 192.104.12.0/24 | 256 | ARIN | US | 22nd Mar 1991 |
| 192.104.138.0/24 | 256 | ARIN | US | 22nd May 1991 |
| 192.104.14.0/24 | 256 | ARIN | US | 28th Mar 1991 |
| 192.104.143.0/24 | 256 | ARIN | US | 23rd May 1991 |
| 192.104.144.0/24 | 256 | ARIN | US | 23rd May 1991 |
| 192.104.145.0/24 | 256 | ARIN | US | 23rd May 1991 |
| 192.104.146.0/24 | 256 | ARIN | US | 23rd May 1991 |
| 192.104.149.0/24 | 256 | ARIN | US | 23rd May 1991 |
| 192.104.150.0/24 | 256 | ARIN | US | 23rd May 1991 |