A user has configured CloudWatch monitoring on an EBS backed EC2 instance. If the user has not attached any
additional device, which of the below mentioned metrics will always show a 0 value?

A.
DiskReadBytes

B.
NetworkIn

C.
NetworkOut

D.
CPUUtilization

Explanation:
CloudWatch is used to monitor AWS as the well custom services. For EC2 when the user is monitoring the EC2 instances,
it will capture the 7 Instance level and 3 system check parameters for the EC2 instance. Since this is an EBS backed
instance, it will not have ephermal storage attached to it. Out of the 7 EC2 metrics, the 4 metrics DiskReadOps,
DiskWriteOps, DiskReadBytes and DiskWriteBytes are disk related data and available only when there is ephermal
storage attached to an instance. For an EBS backed instance without any additional device, this data will be 0.