If the user has not attached any additional device, which of the below mentioned metrics will always show a 0 value?

Explanations:

DiskReadBytes will show 0 as there is no additional device attached, meaning there are no reads from any disk other than the root EBS volume, which does not count in DiskReadBytes.

NetworkIn measures inbound network traffic to the instance. Even with no additional device, network traffic can still occur, so it won’t necessarily be 0.

NetworkOut measures outbound network traffic from the instance. Similar to NetworkIn, network traffic may still occur, meaning it won’t necessarily be 0.

CPUUtilization measures CPU usage on the instance. Even minimal activity would register a non-zero value, so it’s unlikely to remain at 0.