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It is also a snapshot, not a history: a block announced yesterday and withdrawn this morning appears here today.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
85,392 blocks match, ordered by prefix.
| Prefix | Addresses | Registry | Country | Allocated |
|---|---|---|---|---|
| 205.143.16.0/21 | 2k | ARIN |  US | 15th Mar 1995 |
| 205.143.160.0/21 | 2k | ARIN | US | 19th May 1995 |
| 205.143.168.0/21 | 2k | ARIN | US | 23rd May 1995 |
| 205.143.176.0/21 | 2k | ARIN | US | 30th May 1995 |
| 205.143.184.0/21 | 2k | ARIN | US | 30th May 1995 |
| 205.143.24.0/21 | 2k | ARIN | US | 17th Mar 1995 |
| 205.143.56.0/21 | 2k | ARIN | US | 27th Mar 1995 |
| 205.143.80.0/21 | 2k | ARIN | US | 5th May 1995 |
| 205.143.88.0/21 | 2k | ARIN | US | 8th May 1995 |
| 205.143.96.0/21 | 2k | ARIN | US | 11th May 1995 |
| 205.144.0.0/20 | 4.1k | ARIN | US | 21st Feb 1995 |
| 205.144.176.0/20 | 4.1k | ARIN | US | 25th Apr 1995 |
| 205.144.192.0/20 | 4.1k | ARIN | US | 18th May 1995 |
| 205.144.240.0/20 | 4.1k | ARIN | US | 30th May 1995 |
| 205.145.152.0/22 | 1k | ARIN | US | 2nd Oct 2008 |
| 205.145.158.0/24 | 256 | ARIN | US | 11th Jan 1995 |
| 205.145.160.0/24 | 256 | ARIN | US | 15th Mar 1995 |
| 205.145.161.0/24 | 256 | ARIN | US | 13th Dec 2013 |
| 205.145.162.0/24 | 256 | ARIN | US | 13th Dec 2013 |
| 205.145.164.0/22 | 1k | ARIN | US | 13th Dec 2013 |
| 205.145.168.0/24 | 256 | ARIN | US | 13th Dec 2013 |
| 205.145.169.0/24 | 256 | ARIN | US | 13th Dec 2013 |
| 205.145.170.0/24 | 256 | ARIN | US | 13th Dec 2013 |
| 205.145.171.0/24 | 256 | ARIN | US | 27th Mar 2014 |
| 205.145.172.0/23 | 512 | ARIN | US | 13th Dec 2013 |
| 205.145.174.0/24 | 256 | ARIN | US | 13th Dec 2013 |
| 205.145.175.0/24 | 256 | ARIN | US | 13th Dec 2013 |
| 205.145.181.0/24 | 256 | ARIN | US | 13th Dec 2013 |
| 205.145.183.0/24 | 256 | ARIN | US | 13th Dec 2013 |
| 205.145.191.0/24 | 256 | ARIN | US | 2nd Apr 2014 |
| 205.147.112.0/20 | 4.1k | ARIN | US | 25th Feb 2008 |
| 205.147.224.0/21 | 2k | ARIN | US | 1st May 2025 |
| 205.148.128.0/18 | 16.4k | ARIN | US | 5th Apr 1995 |
| 205.148.64.0/18 | 16.4k | ARIN | US | 31st Mar 1995 |
| 205.149.192.0/18 | 16.4k | ARIN | US | 11th Apr 1995 |
| 205.149.96.0/19 | 8.2k | ARIN | US | 17th Mar 1995 |
| 205.151.100.0/24 | 256 | ARIN |  CA | 28th Feb 1995 |
| 205.151.101.0/24 | 256 | ARIN | CA | 28th Feb 1995 |
| 205.151.102.0/24 | 256 | ARIN | CA | 28th Feb 1995 |
| 205.151.103.0/24 | 256 | ARIN | CA | 28th Feb 1995 |
| 205.151.104.0/23 | 512 | ARIN | CA | 28th Feb 1995 |
| 205.151.106.0/23 | 512 | ARIN | CA | 28th Feb 1995 |
| 205.151.108.0/22 | 1k | ARIN | CA | 28th Feb 1995 |
| 205.151.121.0/24 | 256 | ARIN | CA | 28th Feb 1995 |
| 205.151.122.0/23 | 512 | ARIN | CA | 28th Feb 1995 |
| 205.151.128.0/19 | 8.2k | ARIN | CA | 28th Feb 1995 |
| 205.151.160.0/23 | 512 | ARIN | CA | 28th Feb 1995 |
| 205.151.164.0/24 | 256 | ARIN | CA | 28th Feb 1995 |
| 205.151.165.0/24 | 256 | ARIN | CA | 28th Feb 1995 |
| 205.151.166.0/23 | 512 | ARIN | CA | 28th Feb 1995 |