课程名称︰计算机网络
课程性质︰必修
课程教师︰周承复
开课学院：电资
开课系所︰资工
考试日期（年月日）︰2015/11/12
考试时限（分钟）：120
试题 :
Computer Network 2015 Mid-Term Exam
Question: "Basic of Computer Networks and the Internet"
Please fill into the blanks (15%)
a) The amount of time required to push all of a packet's bits into a link is
called ______.
b) The Internet's application layer includes many protocols, such as the ______
protocol (which provides for Web document request and transfer), ______
(which provides for the transfer of e-mail messages), and ______ (which
provides for the transfer of files between two end systems).
c) How many IP Protocols are there in the Internet? ______
d) An application-layer process sends messages into, and receives messages
from, the network through a software interface called a ______. This is also
referred to as an API which stands for ______.
e) Internet protocols are defined in ______.
f) In order to deal with the issue of scale, the DNS uses a large number of
servers, organized in a ______ fashion and distributed around the world. No
single DNS server has all of the mappings for all of the hosts in the
Internet. Instead, the mappings are distributed across the DNS servers. To
a first approximantion, there are three classes of DNS servers