域名服务器DNS（将域名转换为IP地址的一种服务）eg:记不住身份证号，但可以通过独一的称号来知道身份证号

电脑中有一个位置可用来讲域名跟IP配对：C:\Windows\System32\drivers\etc\hosts

hosts文件中的内容

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# Copyright (c) 1993-2009 Microsoft Corp.
#
# This is a sample HOSTS file used by Microsoft TCP/IP for Windows.
#
# This file contains the mappings of IP addresses to host names. Each
# entry should be kept on an individual line. The IP address should
# be placed in the first column followed by the corresponding host name.
# The IP address and the host name should be separated by at least one
# space.
#
# Additionally, comments (such as these) may be inserted on individual
# lines or following the machine name denoted by a '#' symbol.
#
# For example:
#
# 102.54.94.97 rhino.acme.com # source server
# 38.25.63.10 x.acme.com # x client host

# localhost name resolution is handled within DNS itself.
# 127.0.0.1 localhost      环网地址
# ::1 localhost

127.0.0.1 localhost

14.215.177.39  www.zhihu.com    （IP      域名 ）操作行

...............................................................................................................................................................................  

hosts文件中进项上行操作可更改域名

　　1）更改hosts文件

　　2)   cmd中 ping www. ×××.com 查

   百度本来域名为  14.215.177.39

 知乎本来域名为  240e:bf:c800:4200:140::

 注：hosts文件更改后记得覆盖原文件，此处知乎域名仍未更改

 成功操作后知乎域名变成百度域名

 病毒：域名劫持（不好使了，有保护措施）

实例：钓鱼网站通过更改用户的hosts文件伪造淘宝IP引诱付款