The first round was a 90 minutes paper-based technical exam. Totally 10 questions. Had to write the answers on paper. Questions were from three categories: 1) operation system knowledge - concepts of IPC, unix text tools (awk, sed, egrep), sections of a loaded process, etc; 2) C++/STL code review - predict program output, find out bugs; 3) TCP/IP questions - compare TCP and UDP. Basically the questions are not hard. However, the knowledge range is relatively wide.