ubuntu apt-get failed

Err http://mirrors.163.com/ubuntu/ trusty/main libtinfo-dev i386 5.9+20140118-1ubuntu1

Could not resolve 'mirrors.163.com'
Err http://mirrors.163.com/ubuntu/ trusty/main libncurses5-dev i386 5.9+20140118-1ubuntu1
Could not resolve 'mirrors.163.com'
E: Failed to fetch http://mirrors.163.com/ubuntu/pool/main/n/ncurses/libtinfo-dev_5.9+20140118-1ubuntu1_i386.deb Could not resolve 'mirrors.163.com'

E: Failed to fetch http://mirrors.163.com/ubuntu/pool/main/n/ncurses/libncurses5-dev_5.9+20140118-1ubuntu1_i386.deb Could not resolve 'mirrors.163.com'

E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?

原因：
 dns服务器没有配置正确

解决办法：
1、打开文件/etc/resolv.conf在其中添加：
 nameserver 8.8.8.8
 nameserver 8.8.4.4
 search localdomain

2、然后重启网卡：使用命令: sudo ifdown eth0

　　　　　　　　　　　　　sudo ifup eth0

更换源方法

1。点击ubuntu software center

2.进去software source

3.选择要更换的源