6.4.2　host

host命令是用来查询DNS记录的，如果使用域名作为host的参数，命令返回该域名的IP，如下所示：

  1. [root@localhost ~]# host www.google.com www.google.com has address 74.125.128.147
  2. www.google.com has address 74.125.128.103
  3. www.google.com has address 74.125.128.99
  4. www.google.com has address 74.125.128.104
  5. www.google.com has address 74.125.128.105
  6. www.google.com has address 74.125.128.106
  7. www.google.com has IPv6 address 2404:6800:4005:c00::67

大家试一下在浏览器中直接输入任意一个查询到的IP地址，按回车键后是不是可以看到google的主页了？以上命令还可以有第二个参数，该参数必须是一个可用的DNS服务器，也就是使用命令指定的DNS查询域名，而不是用/etc/resolv.conf文件中定义的DNS查询。

  1. [root@localhost ~]# host www.google.com 8.8.8.8
  2. Using domain server: Name: 8.8.8.8
  3. Address: 8.8.8.8#53
  4. Aliases: 
  5. www.google.com has address 74.125.128.147
  6. www.google.com has address 74.125.128.99
  7. www.google.com has address 74.125.128.106
  8. www.google.com has address 74.125.128.103
  9. www.google.com has address 74.125.128.105
  10. www.google.com has address 74.125.128.104
  11. www.google.com has IPv6 address 2404:6800:4005:c00::93