Take an IP and try to look for the domain/host associated with it.
Find A, AAAA, CNAME, MX, NS, TXT, SOA DNS records of a host.
Get approximate IP details.
Check if the URL is banned and marked as safe/unsafe by Google.
Get all possible details about a domain name.
Check whether a website is using the Brotli Compression algorithm or not.
Get all the HTTP headers that an URL returns for a typical GET request.
Make sure your passwords are good enough.