I recently applied in zeta through Linkedin. There were 2 rounds.

In the first round the interviewer asked the below question
There are n biased coins. Find out the probability of getting exactly k heads when n coins are tossed in the same sequence.

I was able to crack the recursive solution later faced some difficulty while building the tabularization approach. Somehow I managed at the end.

The second round was mainly to discuss some OS, networking along with my previous project expertise like (horizontal vs vertical scaling, ACID props, 2 phase commit, SAGA pattern etc.)

Later I got the rejection email from HR.