I prefer to used json to write my ansible playbooks. I'm aware that barely anyone uses json in the real-world ansible community, but I feel safer writing in json during the exam (because who writes yaml with vim anyway?).
I've heard that a script grades the exam, and I'm worried the script may, for example, check for the presence of a "playbook.yml" instead of a "playbook.json" (or yaml syntax in general), as has happened during the course labs.
Is it safe to use json during the exam?
I'm interested in this answer as well. I'd assume that it won't matter if the playbook is in YAML or JSON. (I use vim for YAML, btw).
Anyway, I suspect that it is the end result that matters, the final state, not the playbook that accomplished that state. However, I do not know.
Incidentally, if using vim for YAML, try this in .vimrc
autocmd FileType yaml setlocal ai ts=2 sw=2 et cuc nu
Now, when vim detects that a YAML file is being edited, it uses a 2-space indentation when the Tab key is pressed, highlights columns, auto indents subsequent lines, and displays line numbers.