We have problems downloading updates with "Automatic Updates" engine in Windows XP SP2, I'm not sure if w2k or w2k3 clients have same problems.
If the computer is behind a proxy server, like ISA Server 2000 or any other, it does not start any download because there is something wrong when the engine has to detect if it has conectivity to the AU server. There is not any problem detecting wich updates are needed.
We have found that IF client computer CAN RESOLVE "au.download.windowsupdate.com" IP address AND computer does not have direct access to internet (it's not SecureNAT) but has proxy-server configured, the engine cancels any download with 0x800703eb Error because it thinks it cannot reach the server (but it can using proxy).
If we add static routes to "au.download.windowsupdate.com" IP addresses the engine passes the connectivity check and then it downloads trough proxy server!!! not through direct connection (with the static route) !!!!
This bug is really annoying and should be fixed, but I don't know how to contact microsoft to fix it!
Connectivity check to "au.download.windowsupdate.com" SHOULD BE done through proxy server FIRST if it is configured on client computer!.
Our setup is a typical ISA Server 2000 installation: 2 NIC's ISA Server, internal DNS Server as SecureNAT client and many client computers as FWC and Web Proxy clients with automatic discovery. Internal DNS resolves any external address for all client computers. Like I mentioned before, to bypass the problem I have created a primary dns zone named "au.download.windowsupdate.com" with multiple "A host" entries with IP addresses 126.96.36.199, 191, 192 and so on... (just one A host is enough for testing), then I configured in a test machine static routes to these IP addresses and it starts working!!!!, but download goes through Proxy Server! not trhough static route!.I know that this is not exactly an ISA server issue, but a problem with the "Automatic Updates" or BITS engine. I have tested it with two different proxy servers with same results. But I have post this problem in two different Microsoft newsgroups without any response!.Perhaps someone here can reproduce this issue and report it to Microsoft?.Any idea? Sorry for my bad english.