Which is the dedicated Stack Community to asking questions about network vulnerability scanning? The network can be OT and IT.
I would like to know how they work in details.
Your current question is probably much too broad for any SE site, but the first place to look would be Security. Some of their tags (topics) are vulnerability scanners, vulnerability and known vulnerabilities.
They have many questions about vulnerabilities and similar topics, but please read the linked page carefully before asking your question and act accordingly. Do not post questions of poor quality and/or which don't fit the scope of the site, please. Also, there's a good chance what you actually want to know is already asked and answered there.