Imagine hundreds of computers going out to the internet at 3:00a.m. every morning to get their Microsoft updates. Even on a T1, these computers would not get all of their updates because of bandwidth. Service Pack 3 at over 300 mb would clog your broadband and fail. On a local managed network of 400 computers, the download for Windows XP Professional Service Pack 3 would be 120 gigabytes of data. This failure would leave your network vulnerable with software exploits across your local area network.
Microsoft’s Windows Software Update Services known as WSUS is a free patch management tool that runs on Windows Server. WSUS is the predecessor to SUS or Software Update Services.
Windows Software Update Services downloads the Microsoft updates for your information technology team. These updates are placed in a database on your server so that your client computers (workstations) can connect to the server and receive updates by your LAN. Because SQL drives the database on the server, database delivery is the fastest in the industry. The aforesaid database ensures transactions are delivered fast and accurate. This methodology of obtaining your updates allows for the distribution of service packs, patches and updates through your LAN’s bandwidth.
Client computers in your domain are loaded with a registry patch so that they will report to the server to obtain these files or policies in your domain can specify how they report to your WSUS server.
Your LAN’s bandwidth at 100 mbps or 1 Gbps allows for your servers to obtain the patches and updates up to 600 times faster than using the internet. At a set time, your server uses WSUS to download updates from Microsoft, places them into the database and delivers these to the clients when called upon.
WSUS servers can also be deployed outside of your firewall to deliver updates to mobile computers (laptops) that are assigned to personnel. This allows the laptops to get only the updates you have approved.
As part of a daily routine, IT network personnel can logon to the server and open up Internet Explorer and review the WSUS administration console. With IIS loaded on the server, you can view which workstations received updates and which failed to receive updates. This administration console also allows for the administrator to view downloaded updates and approve those updates that have been tested.
This form of managing updates holds down administrative overhead and holds down cost in small businesses and enterprises while keeping your business secure.
http://technet.microsoft.com/en-us/wsus/default.aspx