In a LAN, which address type is used to identify devices at the network layer?

In a LAN, which address type is used to identify devices at the network layer?

• A. MAC address
• B. Port number
• C. IP address
• D. Hostname

Answer: (C)

At the network layer, the identifier used for devices is an IP address. This logical address lets routers determine how to forward packets toward the destination across networks, and it stays consistent even if hardware changes. On a LAN, you’ll still assign IP addresses to devices so they can be reached beyond the local link, and IPv4 or IPv6 addresses are the ways this layer identifies hosts. In contrast, the MAC address operates at the data link layer and is used to deliver frames within the same local network segment—it's about local delivery to the correct hardware interface on a switch or router. A port number identifies a process on a host at the transport layer, not a device across the network. A hostname is a human-friendly label that resolves to an IP address but is not itself the network-layer identifier. So, the address type used to identify devices at the network layer is the IP address.

At the network layer, the identifier used for devices is an IP address. This logical address lets routers determine how to forward packets toward the destination across networks, and it stays consistent even if hardware changes. On a LAN, you’ll still assign IP addresses to devices so they can be reached beyond the local link, and IPv4 or IPv6 addresses are the ways this layer identifies hosts.

In contrast, the MAC address operates at the data link layer and is used to deliver frames within the same local network segment—it's about local delivery to the correct hardware interface on a switch or router. A port number identifies a process on a host at the transport layer, not a device across the network. A hostname is a human-friendly label that resolves to an IP address but is not itself the network-layer identifier.

So, the address type used to identify devices at the network layer is the IP address.