ubuntu20.0 换源后temporary failure resolving mirrors.aliyun.com的解决

执行更新数据(sudo apt-get update)提示:

Err http://mirrors.aliyun.com trusty Release.gpg
Could not resolve 'mirrors.aliyun.com'
Err http://mirrors.aliyun.com trusty-updates Release.gpg
Could not resolve 'mirrors.aliyun.com'
Err http://mirrors.aliyun.com trusty-backports Release.gpg
Could not resolve 'mirrors.aliyun.com'
Err http://mirrors.aliyun.com trusty-security Release.gpg
Could not resolve 'mirrors.aliyun.com'
Reading package lists... Done
W: Failed to fetch http://mirrors.aliyun.com/ubuntu/dists/trusty/InRelease

出现该错误的原因是我们没有编辑网络DNS配置文件，此时只要编辑网络DNS配置文件即可: 

cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN

nameserver 8.8.8.8
nameserver 8.8.4.4

nameserver 114.114.114.114

然后我们在重启网络： 这里是关键

sudo /etc/init.d/network-manager restart