What type of addressing is used at layer 3 and is typically utilized by routers?

Layer 3 of the OSI model corresponds to the Network layer, where the primary function is routing packets between devices on different networks. The addressing scheme used at this layer is IP addressing. This method assigns unique numerical labels to each device on a network, allowing routers to forward packets based on the destination IP address. Routers examine these addresses to determine the most efficient path for delivering data from the source to the destination across interconnected networks.

In contrast, MAC addressing, operational at Layer 2 (the Data Link layer), is employed primarily within a local network to identify devices uniquely within that network segment. Port addressing, which is at Layer 4 (the Transport layer), differentiates services on a host by allowing multiple applications to communicate over the same IP address. Dynamic addressing refers to the method of assigning IP addresses dynamically through protocols like DHCP, but it is still fundamentally based on IP addresses.

Thus, the correct answer is IP addressing, as it is essential for routing decisions made by routers at Layer 3, facilitating communication across diverse networks.