Question { HP, 41662 }

how Wsus work ? and how the clients are updated automatically?

Answer

WSUS is very uselful tool , to manage centralised patching from one server.
It includes all patches :- Crtitical, Important etc.
WSUS server uses port 443 for HTTPS protocol.

If the above is blocked then you need to allows below urls to obtain updates.

http://windowsupdate.microsoft.com

http://*.windowsupdate.microsoft.com

https://*.windowsupdate.microsoft.com

http://*.update.microsoft.com

https://*.update.microsoft.com

http://*.windowsupdate.com

http://download.windowsupdate.com

http://download.microsoft.com

http://*.download.windowsupdate.com

http://wustat.windows.com

http://ntservicepack.microsoft.com

On WSUS 3.2 and earlier, port 80 for HTTP and 443 for HTTPS

On WSUS 6.2 and later (at least Windows Server 2012), port 8530 for HTTP and 8531 for HTTPS

he firewall on the WSUS server must be configured to allow inbound traffic on these ports.