The nWWN is assigned to which San fabric component?

A Fibre Channel adapter (HBA) carries a vendor-assigned WWNN at the device level, but in the Cisco SAN fabric context the nWWN is specifically associated with the individual Fibre Channel interface rather than the adapter as a whole.

Disks are backend storage media and are not assigned nWWNs - they are accessed through storage controllers or array front-end ports that hold the WWN assignments.

An SFP module is a passive optical transceiver component and is never assigned a WWN of any type, as WWNs apply to logical or virtual Fibre Channel entities.

The nWWN is assigned to a Fibre Channel interface, providing a node-level identity for that port within the SAN fabric for login and discovery purposes. In Cisco MDS NX-OS, each Fibre Channel interface is assigned an nWWN that represents its node identity during fabric login (FLOGI) and enables the fabric to uniquely track and route to that endpoint. This is distinct from the pWWN (port WWN), which identifies the specific port rather than the node it represents.