I've just performed the NSE4 Exam related to the 5.4 version of the FortiOS.
Just to let you know, the exam has specific questions addressed during the official course so, even if the passing score is only 60%, I hardly suggest you to follow that course before attending the exam itself (important information provided).
I would suggest to read and comprehend the admin course carefully plus factor if you have broad exposure in fortigate administration too. experience will help also to pass the exam.good luck to all test takers =)
The Fortinet Security Fabric brings together the concepts of convergence and consolidation to provide comprehensive cybersecurity protection for all users, devices, and applications and across all network edges.