A new server was installed for the purpose of monitoring network traffic. The network has been configured in such a way that all traffic will be mirrored out the port this server is connected to. When

While NIC filtering could limit traffic, the fundamental issue when *all* mirrored traffic isn't seen is the NIC's default behavior of only accepting its own MAC, which is overcome by promiscuous mode.

Port security controls which MAC addresses are allowed on a port; it would typically prevent unauthorized devices from connecting or cause port shutdown, not selectively filter mirrored traffic.

A network interface card (NIC) typically filters incoming frames, only processing those addressed to its own MAC address by default. For a monitoring server to capture all traffic mirrored to its port (e.g., via SPAN or port mirroring), its NIC must be placed in promiscuous mode, allowing it to accept and process all frames, regardless of their destination MAC address.

If the NIC were *in* promiscuous mode, it *would* be seeing all network traffic, contradicting the problem statement that only traffic destined to the server is listed.