Is there any official study guide for this course/exam ?
Thanks in advance
I think the best way to check this is to review the exam objectives outlined here: https://www.redhat.com/en/services/training/ex457-red-hat-certified-specialist-in-ansible-network-au... .
You can also check what's the outline for the related DO457 training in https://www.redhat.com/en/services/training/do457-ansible-network-automation?section=Outline .
Hope this helps