筆試一共5個部分，其中第一部分是C語言的，選擇，改錯，什麼都有，有4頁紙那麼多，沒法抄。把後邊4部分抄回來了，如下。
Part 2. Network
1. please enumerate all TCP/IP protocols for every layer as many as possible based on TCP/IP 5-layer reference model.
2. what is vlan? why we need it?
3. please describe the PPP protocols.
4. please describe the difference between Hub, Switcher and Router.
Part 3. Operating System
1. please describe the difference between process and thread.
2. please list the scheduling mechanisms of a real time OS as you know, and describe their characteristics, respectively.
