最近在安装使用ubuntu，并且配置源文件下载相应gcc，gdb时候，出现错误，提示报错内容为
Err http://mirrors.163.com trusty Release.gpg
Could not resolve 'mirrors.163.com'
Err http://security.ubuntu.com precise-security Release.gpg
Could not resolve 'security.ubuntu.com'
Err http://mirrors.163.com trusty-security Release.gpg
Could not resolve 'mirrors.163.com'
Err http://mirrors.163.com trusty-updates Release.gpg
Could not resolve 'mirrors.163.com'
Err http://mirrors.163.com trusty-proposed Release.gpg
Could not resolve 'mirrors.163.com'
Err http://mirrors.163.com trusty-backports Release.gpg
Could not resolve 'mirrors.163.com'
Err http://us.archive.ubuntu.com precise Release.gpg
Could not resolve 'us.archive.ubuntu.com'
Err http://us.archive.ubuntu.com precise-updates Release.gpg
Could not resolve 'us.archive.ubuntu.com'
Err http://us.archive.ubuntu.com precise-backports Release.gpg
Could not resolve 'us.archive.ubuntu.com'
Reading package lists... Done
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/Release.gpg Could not resolve 'us.archive.ubuntu.com'
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-updates/Release.gpg Could not resolve 'us.archive.ubuntu.com'
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-backports/Release.gpg Could not resolve 'us.archive.ubuntu.com'
W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/precise-security/Release.gpg Could not resolve 'security.ubuntu.com'
W: Failed to fetch http://mirrors.163.com/ubuntu/dists/trusty/Release.gpg Could not resolve 'mirrors.163.com'
W: Failed to fetch http://mirrors.163.com/ubuntu/dists/trusty-security/Release.gpg Could not resolve 'mirrors.163.com'
W: Failed to fetch http://mirrors.163.com/ubuntu/dists/trusty-updates/Release.gpg Could not resolve 'mirrors.163.com'
W: Failed to fetch http://mirrors.163.com/ubuntu/dists/trusty-proposed/Release.gpg Could not resolve 'mirrors.163.com'
W: Failed to fetch http://mirrors.163.com/ubuntu/dists/trusty-backports/Release.gpg Could not resolve 'mirrors.163.com'
W: Some index files failed to download. They have been ignored, or old ones used instead.
如果确保更新源没错，那么可能是DNS配置的问题，解决方法：
1、运行DOS，输入ipconfig /all查看DNS的地址
2、ubuntu中获取管理员权限
3、vi /etc/resolv.conf打开配置文件，并且在最后添加nameserver ***.***.***.***(DNS)的地址，回车，再添加，search localdomain
4、重新执行sudo apt-get update
问题解决。。。