Leonidas has been told that there is a layer 3 problem with his network. Which of the following is associated with layer 3 in the OSI model?

The Network layer, or layer 3, uses IP addresses for logical addressing. TCP and UDP protocols are used at the Transport layer (layer 4), hardware addresses (MAC addresses) are at the Data Link layer (layer 2), and sending and receiving bits via hardware is done at the Physical layer (layer 1).