On the Pure Storage FlashArray//C R4 (as well as the //XL and //E series architectures), the onboard 100Gb/s Ethernet LOM (LAN on Motherboard) ports-specifically eth0 and eth1-are purpose-built and strictly reserved for DirectFlash Shelf (DFS) connectivity.
Pure Storage uses these dedicated 100GbE ports to run NVMe over RoCE (RDMA over Converged Ethernet), effectively extending the array's internal PCIe backplane to additional backend storage shelves. Because these ports are hardcoded exclusively for back-end shelf expansion, the Purity operating environment fundamentally restricts them from being assigned IP addresses for front-end host I/O services. Therefore, an administrator will be completely unable to configure eth0 or eth1 for iSCSI, NVMe/TCP, or Replication. Front-end iSCSI services must instead be configured on the dedicated Host I/O PCIe cards (which typically appear as eth2, eth3, etc., depending on the slot configuration).
Here is why the other options are incorrect:
The ports are designated for Management connectivity (A): On modern FlashArrays, dedicated management ports are typically out-of-band 1GbE/10GbE RJ45 ports (often designated as vir0 or specific management eth ports on older hardware), not the ultra-high-speed 100Gb/s QSFP28 ports.
The DAC cables are not compatible with the array's ports (B): While incompatible cables can prevent a link from coming up physically, the specific reason the administrator cannot configure the ports for iSCSI in the Purity software is due to the port's hardcoded role (DFS), not the physical cable type.