Norton Pop Up

I am new to Norton.  Now when I am on my computer from time to time I get a pop up that says a certain web site or ??? wants permission to download to my computer.  For instance, just got one from PubSubAgent a184-84-222-74.  Norton wants to know if I will allow this or not.   ??????????  How do I know what this is and if it is safe to "allow" or not ??