Got call fro directly from zscaler HR. They explained the post and then within 2 days she arranged 1st round of interview. Due to covid19 the whole process was on zoom. I have given 4 round. In each round they have asked 2-3 questions. Questions were related to C programming like extern, volatile , static functions and variables, tree, bitmap(4-5 questions), array, strings, linked list, stack and projects that you did. I did 3 round well and in 4th round I was stuck in small problem and he helped me to write the code and I wrote it also but interview result was negative. And it's almost 3 month they didn't inform me.