操作系统：Ubuntu 12.04 LTS
在Ubuntu操作系统中，使用apt-get命令安装所需的开发软件非常方便，但也有不少时候由于链接不上软件源而不能正常安装，于是很多人都会想到使用sudo
apt-get update命令来更新软件源，而恰恰这时屋漏偏逢连夜雨，更新命令也不能正常工作，出现大量“Failed to fetch”的错误。
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/precise-updates/main/binary-i386/Packages Something wicked happened resolving 'archive.ubuntu.com:http' (-5 - No address associated with hostname)
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/precise-updates/restricted/binary-i386/Packages Something wicked happened resolving 'archive.ubuntu.com:http' (-5 - No address associated with hostname)
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/precise-updates/universe/binary-i386/Packages Something wicked happened resolving 'archive.ubuntu.com:http' (-5 - No address associated with hostname)
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/precise-updates/multiverse/binary-i386/Packages Something wicked happened resolving 'archive.ubuntu.com:http' (-5 - No address associated with hostname)
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/precise-updates/main/i18n/Translation-en_US Something wicked happened resolving 'archive.ubuntu.com:http' (-5 - No address associated with hostname)其实，解决这个问题十分简单，只要设置妥当DNS服务器即可.
$ sudo vim /etc/resolv.conf nameserver 8.8.8.8
nameserver 8.8.4.4
然后重启网络服务：sudo etc/init.d/networking restart
再次执行sudo
apt-get update命令，结果一切正常。
我按照这个改了之后发现依然不行，后来点击链接进入该链接的上一级目录，发现是该目录下没有所请求的资源，而不是网络的问题。
