Zscaler C++ Developer interview questions

There are 3 Technical Interviews and 1 HR Interview. It is a virtual Interview, In 1st They ask technical questions based on Computer Network, and after qualified, the candidate has to give 2nd Round. In 2nd round, I asked about Operating System and 2 easy coding questions, In Operation System they go very deep about all the concepts I answered a few of them but I understand that this is not up to the mark, So unfortunately I did not qualify in 2nd round.