If there are many roaming WSUS clients on your network, who often log on to your network from different locations, you may want to configure WSUS so that these computers always get their updates from the nearest WSUS server. This procedure presupposes that you have several different DNS subnets in your network and that you want to install WSUS servers in the subnets. There is one WSUS server per region and each region is a DNS subnet. All clients are pointed to the same WSUS server name, which resolves in each subnet to the nearest WSUS server.
Warning: DNS setup involve in these procedure. Don’t modify DNS if you aren’t sure what you doing.
Identify the servers to use as WSUS servers
Identify one server in each of the subnets that you plan to use as a WSUS server. Keep a record of their IP addresses and hostnames. Just to keep it simple, use port 8530 in all the hosts.
Set up the host names on the DNS server
Set up as many DNS host (A) resource records as there are planned WSUS servers. Make sure that each of the planned WSUS servers has the same host name. To set up the host names on the DNS server
1. Launch the DNS console.
2. Click Action, and then click New Host (A).
3. In the New Host dialog box, type the server name in the Name box.
4. Type the appropriate IP address in the IP address box.
5. Click Add Host.
6. Repeat this procedure for the rest of the planned WSUS servers.
Set up the DNS server for netmask ordering and round robin
With netmask ordering, you restrict name resolution to computers in the same subnet, if there are any. With round robin, if there are multiple name resolutions, the result that is returned will rotate through the list of available hosts. Therefore, if there is a subnet without a WSUS server, host name resolution for clients in that subnet will rotate through the list of WSUS servers in the other subnets. To set up netmask ordering and round robin on the DNS server
1. In the DNS console, right-click the DNS server node, click Properties, and then click the Advanced tab.
2. In the Server options box, select the Enable round robin and Enable netmask ordering check boxes.
3. Click OK.
Install and configure the WSUS servers
Set up and configure the WSUS servers in the different subnets. See complete step by step guide on How to Install and configure WSUS 3.0 SP2 for details.
WSUS Clients OS are Windows XP SP2, Vista, Windows7, Windows server 2003 SP2 and Windows Server 2008. When you set up WSUS client computers (see the link mentioned in step4 for GPO config), make sure to use the same host name you have set up as the WSUS server. Configure GPO and WSUS to deliver Windows update to clients. All the clients should point to http://ServerName:8530 and target group.