Should I let malwaredomainlist.com connect to the net?
I found the answer to my own question. You can see both the question and answer here. The problem seems to have to do with a firefox plugin named uBlock Origin. In the preferences pane you will find a list of addresses which you can enable or disable. the addresses are related to websites which update maleware sites, etc. It Looks like the malewaredomainlist.com was one of those addresses. In short, it is safe to let it connect to the Net.