下列选项中属于输入输出异常的是___________。
A. NullpointerException
B. SecurityException
C. ArrayOutofBoundsException
D. IOException
1. Why are protocol messages o most Internet applica-tions ASCII and variable length?
2. Why do servers running over TCP and UDP haveconcurrent and iterative implementations, respectively?
3. How do DNS servers resolve a domain name into anIP address?