File reputation is used by Symantec to check the credibility of file. symantec uses various metrics to check this out. it is used to determine the unknown or new files.
check this article, just in case you want to allow your machines to connect to reputation server.
Required exclusions for proxy servers to allow Endpoint Protection to connect to reputation and licensing servers
if you don't want them to connect to reputation server then simply follow the below steps,
1 In the console, select Clients then click the Policies tab.
2 In the Settings pane, click External Communications Settings.
3 Click the Submissions tab.
Uncheck what you don't want to submit to Symantec.
and finally,
by default sep client will look upto SEPM for definitions. just to be sure that clients do go online to download definitions
1 In the console, select policies tab then click the liveupdate polices.
2 double click on the policy assigned to the clients group and select the Server settings under windows settings
make sure to uncheck the Use a LiveUpdate Server
now you are all set