I read, from https://docs.moodle.org/20/en/User_site_capacities (no page seems to exist for 3.0+) :
... The exact number of users depends on your hardware/software/network combination. Usually the amount of memory installed (RAM) is the deciding factor but a faster overall processor speed will also help in reducing waiting times for pages to load.
The general rule of thumb for a single server is that the approx max concurrent users = RAM (GB) * 50 and the approx max browsing users = Approx max concurrent users * 5. As an example, a university with 500 total computers on campus and 100 concurrent users at any time will need approx 2GB of RAM on the one server to support the number of concurrent users...
Our government has state wide exams. According to the above rule of thumb and with a 100 000 / 50 = 2 000 GB = 2 TB web server or bigger, could 100 000 users take exactly the same quiz simultaneously? Also, would the waiting time for feedback during the quiz be reasonable?
Best regards to all.