Did you setup a policy to tell those machines to change where to look for SWU to the new one you listed inside of your Network Segments settings?

Shouldn't need to do that. Assigning the default Software Update server in the Network Segment should be enough, provided everything is set up correctly (both the SWU server info and the address range in the Network Segment)

However, to the OP, do these happen to be 10.8 Macs you're seeing this issue with? There is a (now) known issue under certain circumstances with 10.8 and SUS assignments in Casper Suite. I wonder if you're running into that.

@hkim
I didn't think I had to (as mm2270 mentioned), but yes, I created such a policy. Still didn't work.

@mm2270:
All my test machines are 10.8, yes. I'll have a look in the discussions for the issue you're mentioning. Thanks.

Do this if you can on one of your 10.8 Macs that should be pulling updates from your SUS-

defaults read /Library/Preferences/com.apple.SoftwareUpdate

Take a look at the first CatalogURL line, if its there. It may read as the server address of your SUS, but see if there is a trailing space at the end of the URL. In other words, it should read something like:

CatalogURL = "http://192.168.1.200:8088/index.sucatalog";

but it may in fact read as:

CatalogURL = "http://192.168.1.200:8088/index.sucatalog ";

Note the space at the end right before the closing quote mark.

If you see that, then that's the problem. In some cases, the JSS is adding a trailing space at the end of the URL, which apparently causes Mountain Lion to default back to Apple's servers. Why it doesn't just fail since the address is invalid is unknown to me. Apple trying to be 'customer oriented' I guess. : /

Sorry, I meant return and say thanks. This was the issue I was seeing.

Throwing my 2¢ into this as well. I could get a report that the ASUS was reporting to the correct location (no extra space either) but anything that was controlled via JAMF for ASUS address failed. Even if I manually ran a "defaults write..." it reported the correct address but didn't work.

If I removed anything related to JAMF for controlling the ASUS and just created a policy that ran the "defaults write..." to the correct address seems to resolve for me.