Hi @Sandeep K.,
every call in your platform between client and service has a general failure rate; ideally near zero.
Dynatrace will notice, if the rate is increased in comparism to the last seven days (if I am not wrong).
In this case, you will see a problem or get a notification (depends on your configuration).
What Jan said +1.
Another way to look at this is to go into the Transactions & Services view within Dynatrace, select the Failure Rate column, then switch to the Graph view. This will give you a historical perspective of failure rates over time with the large contributors showing up in the graph. Be sure to select a time range which covers the time when the increase was reported.