WSUS troubleshooting

This artilcle is in english to be useful to more people.

I've spent some time to setup wsus on my environment and other time to maintain that and to approve the updates but oftent I saw client that are not loggin on the wsus server. 
Here you can find some useful workaround:

Situation: - There's a group policy that sets WSUS on the clients (not mandatory, you can use also a script see: http://msmvps.com/blogs/athif/pages/Manually-Configure-WUA.aspx)
- My wsus have a DNS alias that points on the correct server (just for future upgrades, this avoid change group policy or settings on the clients)

To be sure that your client is receiving properly updates:
1. check if your client receive the correct policy, with group policy result wizard or directly on the client looking the content of this registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate
you should see this two values:

"WUServer"="http://YOUR-WSUS-SERVER"
"WUStatusServer"="http://YOUR-WSUS-SERVER"

 2. Check if dns resolution works correctly:
nslookup YOUR-WSUS-SERVER<.name.local> 

3. Chek with internet explorer if you can access the wsus website with the address on the key in point 1


At this point all should work and if you use wuauclt /detectnow after some time you should see the client registered on wsus server and probably some updates needed.

If the client still not connect to the server use the WSUS client diagnostic tool: http://download.microsoft.com/download/9/7/6/976d1084-d2fd-45a1-8c27-a467c768d8ef/WSUS%20Client%20Diagnostic%20Tool.EXE
(see other tools here: http://technet.microsoft.com/en-us/windowsserver/bb466192.aspx)

Run the client in a command window and see if all the test are: PASSED
If not look at the Winhttp proxy setting section and see if there's a proxy defined here.

In my case was as: (you can read) "proxy:" and then "avoid proxy for 192.168.1.25"

This lines was the ones that avoid access to WSUS, the local system account is using the string as a proxy and the server is not in the "avoid proxy list".

use the command proxycfg  to see which is the configuration and eventually use: proxycfg -d to go diretct or proxycfg -p to set parameters correctly.

This worked for me like a charm.