Posted 27 June 2009 - 10:53 AM
Surprisingly enough, this can be done both ways. But reading that you are at a university, they are most probably using an appliance to do this. There are routers and network bandwidth management devices which will give you this much control over what is and is not downloaded to your computer.
Equipment like Cisco routers, Sonicwall Routers, Saint Bernard boxes, and so on have added controls added to them ( at an added cost ) to allow this type of control. These things can also be accomplished through Group Policy in a Windows Domain environment. You can set the policies to allow only "approved" extensions through Internet Explorer but as most people have found out, if you have Firefox or Chrome or most any other browser, you can walk around these settings.
In a university environment, they have so much bandwidth to distribute to "everyone" including their own data center. And also with the RIAA cracking down so much on the proliferation of "sharing" music and files, universities are installing these types of equipment to keep their liability over what is allowed over "their" network down to a minimum.
Hope this sheds some light,
"Admire those who attempt great things, even though they fail."