几个关于网络的笔试题

1) The Transport layer defined in Open Systems Interconnections model is used to:
A) Initiate the Login authentication
B) Initiate the transfer of data between two computers
C) Transfer and receive the data reliably
D) Decide on the route taken to transfer the data
2) Which of the following is the measure of the range of frequencies a communication signal occupies?
A) Radian
B) Frequency modulation
C) Dynamic range
D) Bandwidth
3) SMTP was basically developed to:
A) Send and receive textual email
B) Only for sending mails
C) Filter spam mails
D) All the options
74) If you want to have 12 subnets with a Class C network ID, which subnet mask would you use?
A) 255.255.255.240 B) 255.255.255.252 C) 255.255.255.248 D) 255.255.255.255

哪位大侠99小弟，谢谢了！