DNS解析问题，在/etc/resolv.conf文件中加如下一行：

nameserver 8.8.8.8

即使用谷歌的域名服务器

 

 

如下问题都是DNS解析问题：

apt-get update 异常 Temporary failure resolving

 

Error response from daemon: Get https://registry-1.docker.io/v2/: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)