题目内容
(请给出正确答案)
[主观题]
The essence of(74) is the invention of a hierarchical, domain-based naming scheme. It is p
The essence of(74) is the invention of a hierarchical, domain-based naming scheme. It is primarily used for mapping host names and e-mail destinations to IP addresses.
A.DNS
B.NNTP
C.CDP
D.FTP
![](https://lstatic.shangxueba.com/sxbcn/h5/images/tips_org.png)