Internal Control

Sir you said in the lectures that auditors there are two ways to carry audit trusting the internal control or not trusting the internal control. but before we decide whether or not to trust the internal controls we need to know about the system. is this the reason why we record the system so we have a better understanding on the controls in place and weather to rely on them or not. Also is this done at the beginning of the audit?before planning and also testing the controls?