安装完Ubuntu后为找一个合适的更新源费了好大力气，都是从网上搜索得来的。其中cn99的最快。保存下来下次备查。
Archive.ubuntu.com （欧洲，官方源）
deb http://archive.ubuntu.com/ubuntu/ feisty main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu/ feisty-security main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu/ feisty-updates main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu/ feisty-proposed main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu/ feisty-backports main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu/ feisty main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu/ feisty-security main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu/ feisty-updates main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu/ feisty-proposed main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu/ feisty-backports main restricted universe multiverse
Ubuntu.cn99.com （江苏省常州市电信）
deb http://ubuntu.cn99.com/ubuntu/ feisty main restricted universe multiverse
deb http://ubuntu.cn99.com/ubuntu/ feisty-security main restricted universe multiverse
deb http://ubuntu.cn99.com/ubuntu/ feisty-updates main restricted universe multiverse
deb http://ubuntu.cn99.com/ubuntu/ feisty-proposed main restricted universe multiverse
deb http://ubuntu.cn99.com/ubuntu/ feisty-backports main restricted universe multiverse
deb-src http://ubuntu.cn99.com/ubuntu/ feisty main restricted universe multiverse
deb-src http://ubuntu.cn99.com/ubuntu/ feisty-security main restricted universe multiverse
deb-src http://ubuntu.cn99.com/ubuntu/ feisty-updates main restricted universe multiverse
deb-src http://ubuntu.cn99.com/ubuntu/ feisty-proposed main restricted universe multiverse
deb-src http://ubuntu.cn99.com/ubuntu/ feisty-backports main restricted universe multiverse
Mirror.lupaworld.com （亚洲地区官方更新服务器）
deb http://mirror.lupaworld.com/ubuntu feisty main restricted universe multiverse
deb http://mirror.lupaworld.com/ubuntu feisty-security main restricted universe multiverse
deb http://mirror.lupaworld.com/ubuntu feisty-updates main restricted universe multiverse
deb http://mirror.lupaworld.com/ubuntu feisty-backports main restricted universe multiverse
deb-src http://mirror.lupaworld.com/ubuntu feisty main restricted universe multiverse
deb-src http://mirror.lupaworld.com/ubuntu feisty-security main restricted universe multiverse
deb-src http://mirror.lupaworld.com/ubuntu feisty-updates main restricted universe multiverse
deb-src http://mirror.lupaworld.com/ubuntu feisty-backports main restricted universe multiverse
中国 台湾省台湾大学
deb http://ubuntu.csie.ntu.edu.tw/ubuntu/ feisty main restricted universe multiverse
deb-src http://ubuntu.csie.ntu.edu.tw/ubuntu/ feisty main restricted universe multiverse
deb http://ubuntu.csie.ntu.edu.tw/ubuntu/ feisty-updates main restricted universe multiverse
deb-src http://ubuntu.csie.ntu.edu.tw/ubuntu/ feisty-updates main restricted universe multiverse
deb http://ubuntu.csie.ntu.edu.tw/ubuntu/ feisty-backports main restricted universe multiverse
deb-src http://ubuntu.csie.ntu.edu.tw/ubuntu/ feisty-backports main restricted universe multiverse
deb http://ubuntu.csie.ntu.edu.tw/ubuntu/ feisty-security main restricted universe multiverse
deb-src http://ubuntu.csie.ntu.edu.tw/ubuntu/ feisty-security main restricted universe multiverse
deb http://ubuntu.csie.ntu.edu.tw/ubuntu/ feisty-proposed main multiverse restricted universe
deb-src http://ubuntu.csie.ntu.edu.tw/ubuntu/ feisty-proposed main restricted universe multiverse
这个网址还可以根据你选择的区域自动生成sources.list文件，
http://www.ubuntulinux.nl/source-o-matic 使用 sudo gedit /etc/apt/sources.list 打开sources.list文件，选择上面合适的服务器内容复制到sources.list文件中。然后执行下列命令进行更新，
sudo apt-get update
sudo apt-get dist-upgrade