I am considering purchasing an rv042 for a client that needs WAN failover. I was concerned though as whether or not the router will actually be aware if the WAN port drops signal or does it just listen for ethernet traffic from the DSL modem ethernet port. ie does it use something along the lines of a keep-alive to test WAN connectivity. I understand the dual WANs are mostly for load-balancing (yes or no?) but I need the feature more for failover. Thanks for help in advance.