Updating windows 2016 core
If you want to check only for recommended updates go ahead and press R, but I I usually go for all. Checking for updates will take a few minutes and at the end you will be presented will all the available updates that apply to the server.
Also, you can choose to revoke the operation and not install any updates, install just a single one or install all. Another way to check for updates and install them is to use a tool like Core Configurator for 2008 R2 or Corefig for Windows server 2012/R2.
After all the updates were installed you will be asked to reboot the server, so click Yes on the message box button to do so. Just mount the ISO (if you are using the ISO version of the utility not the ZIP one) and run Start_or Start_depending on which of the two utilities are you using.
As you can see, you can change a lot of settings in the OS using this tool, but since we are interested in updates only, click the Control Panel button then Windows Updates.
And you do this from a single computer, your technician computer, but there are networks out there that have just a few servers, and some of them are installed without a GUI, and now the patching process just got a little bit complicated.
Patching the core edition of Windows server can be done in multiple ways, and the most popular one is using the built-in server configuration menu.
By typing sconfig in the command prompt it will open the menu where you can do a lot of server configurations.
The basic method was to use Hyper-V Connect to attach to each virtual machine, log in, and run an integration services update from VMguest. This manual task would require a maintenance window for each virtual machine.
Because this was a manual task and introduced downtime, I suspect that many just decided to live without the updates, possibly falling out of support and becoming vulnerable to any otherwise-fixed security problems.