When an Interest packet arrives, an NDN router first checks the Content Store for matching data; if it exists in the router returns the Data packet on the interface from which the Interest came. Otherwise the router looks up the name in its PIT, and if a matching entry exists, it simply records the incoming interface of this Interest in the PIT entry. In the absence of a matching PIT entry, the router will forward the Interest toward the data producer(s) based on information in the FIB as well as the router's adaptive Forwarding Strategy. When a router receives Interests for the same name from multiple downstream nodes, it forwards only the first one upstream toward the data producer(s).