Functionalities of external auditor

Can i know the functionalities of external auditor?
 

Answer:

Basically review that all requirements established by the standard are in place in the organization. To do this, the lead auditor needs to perform interviews with staff of the organization, perform tests of security controls compliance, review of documentation, etc. Finally at the end of the audit the Lead Auditor also need to develop a report with all deviations detected, and it needs  to be presented to the company. 
If you are interested in become a lead auditor, this article can be interesting for you “How to become ISO 27001 Lead Auditor” : https://advisera.com/27001academy/knowledgebase/how-to-become-iso-27001-lead-auditor/
Finally, maybe this article can be interesting for you "Infographic: The brain of an ISO auditor - What to expect at a certification audit" : https://advisera.com/articles/infographic-the-brain-of-an-iso-auditor-what-to-expect-at-a-certification-audit/