Cognizant Software Developer interview questions

There were three rounds of telephonic interview to extend an offer. All the three telephonic calls were at random time on a scheduled day. First interview: Included basic/intermediate technology questions. It lasted for about 20 minutes. This interview sounded like they're validating if the candidate is genuine. Second interview: Interviewed more about current and previous work projects with extended questions on the technologies that I've worked on. Lasted for about 40 minutes Third interview: This was the last interview which included interviewers from the client location and last about an hour. After all the rounds of interview they've extended an offer after 1 1/2 month. Later they've postponed joining date by another 1 1/2 month saying due to client project was being delayed.