For those a bit confused: This subdomain redirects to https://beta.shodan.io/host/$YOUR_REMOTE_ADDR. This runs a search against their existing database of information. Shodan has an army of bots that crawl the entire Internet and stores what it finds along the way. Folks generally pay Shodan for access to these notes.
The site returns various HTTP error codes based on the results of that lookup, or shows a fancier page with open ports and other information it has on that IP address. (Example: https://beta.shodan.io/host/1.1.1.1)
There is no active scan occurring here. (But you could be hinting to Shodan that these particular IPs are valid though!)
>(I wouldn't rule out that you may be hinting to Shodan that these particular IPs are valid though!)
For those of us on IPv4, eh. Only 4 billion addresses, and with a lot of that itself tied up in various large /8s to a few specific organizations many of which can be assumed to be beyond casual level, it's just no longer a real haul to scan everything all the time at a basic level. Plus for those of us browsing from our main address we're leaving a trail all over the web anyway through a host of poorly secured servers. So I while I don't disagree it's worth thinking about information leaks and honey pots and the like whenever dealing with infosec in any way, in this specific case I also don't think this reveals anything of significant value.