title: How windows update agent WUA identify KB's to be installed?
body: <p>I was trying to find what updates can be applicable to the given system? I saw <a href="https://docs.microsoft.com/en-us/windows/desktop/wua_sdk/searching--downloading--and-installing-updates" rel="nofollow noreferrer">WUA</a> Api calls page. I was wondering how Windows update agent works? How windows decides which KB's they need to install? Is there any central place like registry where I know different components installed or default with version information? and then decides patches? </p>
  
  <p>For example, to install dot net KB's or IE KB's how do I find dot net, IE, vbscript like components first on the system?</p>
  
  <p>Any idea?</p>