OSI Model Layer Responsible for IP Addressing

The Network layer (Layer 3) of the OSI model is responsible for logical addressing and routing. This includes assigning IP addresses to hosts so they can be uniquely identified across networks. While the Data Link layer (Layer 2) handles physical addressing via MAC addresses, and the Application layer (Layer 7) deals with user interfaces, it is strictly the Network layer that defines the structure of IP packets and their addressing scheme.

Regarding the provided comments, one user correctly identifies Layer 3 as responsible for logical addressing like IPv4 and IPv6, supporting option C. Another comment incorrectly suggests Option B (Application), likely confusing application-layer services (like DHCP) with the OSI layer definition itself. DHCP operates at the Application layer but delivers configuration to the Network layer; however, the question asks which layer is responsible for assigning (in terms of address space definition and packet handling) or typically associated with IP addressing in exam contexts. In CompTIA Network+ doctrine, IP addressing is a core function of the Network layer.

This knowledge extends to understanding how different layers interact: if you are troubleshooting connectivity issues, knowing whether a problem is at the Network layer (IP conflict, wrong subnet mask) versus the Data Link layer (switch port error) is critical. Getting this wrong could lead to misdiagnosing a routing issue as an application failure. The key distinction is between logical addressing (Network/IP) and physical addressing (Data Link/MAC).