Exam NS0-162 topic 1 question 22 discussion

BC: Historically (7-Mode/clustered Data ONTAP), NetApp had recommended that flow control be disabled on all network ports within a NetApp Data ONTAP cluster. This approach is no longer the case. Guidance in this area has since changed, the new recommended best practice is as follows: Disable flow control on cluster network ports in the Data ONTAP cluster. Flowcontrol on the remaining network ports (the ports that provide data, management, and intercluster connectivity) should be configured to match the settings within the rest of your environment.

AC are right ones as in question it's clearly mentioned that user cannot disable flow control on CNA. As NetApp's current recommendation for flow control is to be disabled on the cluster network, but makes no recommendation for the data network. The only option is to enable flow control on data NW.

Flow control is a mechanism that allows a network device to pause the transmission of data from another device when its receive buffer is full. Flow control can be useful to prevent packet loss and congestion in some scenarios, but it can also cause performance degradation and latency in others1 According to the NetApp best practices, flow control should be disabled on cluster network ports in the ONTAP cluster. This is because flow control can interfere with the cluster heartbeat mechanism and cause unnecessary failovers or false alarms Flow control should also be disabled on data network ports in the ONTAP cluster, especially when using SMB protocol. This is because SMB is sensitive to latency and flow control can introduce delays and jitter in the data transmission.

BC https://kb.netapp.com/Advice_and_Troubleshooting/Data_Storage_Software/ONTAP_OS/What_are_the_flow_control_best_practices_for_Ethernet%3F

Consensus

Disable flow control end-to-end on cluster network ports and is disabled by default

B and C is Correct

Clustered Data ONTAP / ONTAP 9 Flow control recommendations: Disable flow control on cluster network ports in the Data ONTAP cluster. Flowcontrol on the remaining network ports (the ports that provide data, management, and intercluster connectivity) should be configured to match the settings within the rest of your environment.

B,C is correct. https://kb.netapp.com/Advice_and_Troubleshooting/Data_Storage_Software/ONTAP_OS/What_are_the_flow_control_best_practices_for_Ethernet%3F#Clustered_Data_ONTAP_.2F_ONTAP_9_Flow_control_recommendations: