Which of the following is a valid Replica Set configuration if you want:

1-Have 3 copies of everything

2- That RS3 is never primary

2- That RSI and RS2 can be primary?

You had to see the different configurations, RS3 could be hidden or priority 0 (But not a referee because we need

3 replicas), while RSI and RS2 could NOT have priority 0 or be hidden or anything like that

In a 4-member RS RSO , RSI, RS2 and RS3 + Referee, RSO (primary) falls after some write operations that have

replicated RSI and RS2 (but NOT RS3), who can get up as the new primary?

The configuration comes and in it we see that RS2 has a hidden: true (or a priority: 0, (I don't remember)