1.软件源下载慢问题
备份软件源：sudo cp /etc/apt/sources.list /etc/apt/sources.list
打开sources.list：sudo gedit /etc/apt/sources.list
把原有deb开头的内容全部去掉，联网状态下，把下面的源一组一组地拷进去（保证每次只拷贝一组），具体也用不着那么壮烈，可以借鉴旁边的推荐意见试试其中几个。每送进一组，Ctrl+S保存，启动更新管理器，点击“检查更新”，这时Ubuntu就会从你设定的源下载软件列表，你这时观察一下下载速度，如果很快的话，就选他了！（参考：我使用徐州校园网电信，教育网连接时厦门大学的非常快）。
此外，也并不能完全照着拷贝这些，Ubuntu每个稳定版本都有一个代号，譬如8.04叫hardy，9.10叫karmic，10.04叫lucid，有些软件源为了区分版本有这个代号。相信你的安装光盘应该有这个代号，具体软件源最好是到网上查一下某版本的软件源，查不到的话，直接把下面软件源里的hardy替换成你的版本的代号即可
Ubuntu.cn99.com更新服务器（江苏省常州市电信，推荐电信用户使用）：deb intrepid main restricted universe multiversedeb intrepid-security main restricted universe multiversedeb intrepid-updates main restricted universe multiversedeb intrepid-proposed main restricted universe multiversedeb intrepid-backports main restricted universe multiversedeb-src intrepid main restricted universe multiversedeb-src intrepid-security main restricted universe multiversedeb-src intrepid-updates main restricted universe multiversedeb-src intrepid-proposed main restricted universe multiversedeb-src intrepid-backports main restricted universe multiverse
台湾大学更新服务器（推荐网通用户使用，强烈推荐此源，比较完整）：deb intrepid main restricted universe multiversedeb-src intrepid main restricted universe multiversedeb intrepid-updates main restricted universe multiversedeb-src intrepid-updates main restricted universe multiversedeb intrepid-backports main restricted universe multiversedeb-src intrepid-backports main restricted universe multiversedeb intrepid-security main restricted universe multiversedeb-src intrepid-security main restricted universe multiversedeb intrepid-proposed main multiverse restricted universedeb-src intrepid-proposed main restricted universe multiverse
厦门大学更新服务器（教育网服务器）：deb ftp://ubuntu.realss.cn/ubuntu/ intrepid main restricted universe multiversedeb ftp://ubuntu.realss.cn/ubuntu/ intrepid-backports restricted universe multiversedeb ftp://ubuntu.realss.cn/ubuntu/ intrepid-proposed main restricted universe multiversedeb ftp://ubuntu.realss.cn/ubuntu/ intrepid-security main restricted universe multiversedeb ftp://ubuntu.realss.cn/ubuntu/ intrepid-updates main restricted universe multiversedeb-src ftp://ubuntu.realss.cn/ubuntu/ intrepid main restricted universe multiversedeb-src ftp://ubuntu.realss.cn/ubuntu/ intrepid-backports main restricted universe multiversedeb-src ftp://ubuntu.realss.cn/ubuntu/ intrepid-proposed main restricted universe multiversedeb-src ftp://ubuntu.realss.cn/ubuntu/ intrepid-security main restricted universe multiversedeb-src ftp://ubuntu.realss.cn/ubuntu/ intrepid-updates main restricted universe multiverse
对于电信网络用户，推荐CN99的源，速度非常快。deb hardy main restricted universe multiversedeb hardy-security main restricted universe multiversedeb hardy-updates main restricted universe multiversedeb hardy-proposed main restricted universe multiversedeb hardy-backports main restricted universe multiversedeb-src hardy main restricted universe multiversedeb-src hardy-security main restricted universe multiversedeb-src hardy-updates main restricted universe multiversedeb-src hardy-proposed main restricted universe multiversedeb-src hardy-backports main restricted universe multiverse
推荐网通用户使用台湾大学的源：deb hardy main restricted universe multiversedeb-src hardy main restricted universe multiversedeb hardy-updates main restricted universe multiversedeb-src hardy-updates main restricted universe multiversedeb hardy-backports main restricted universe multiversedeb-src hardy-backports main restricted universe multiversedeb hardy-security main restricted universe multiversedeb-src hardy-security main restricted universe multiversedeb hardy-proposed main multiverse restricted universedeb-src hardy-proposed main restricted universe multiverse
校园网的朋友，推荐厦门大学Ubuntu服务器：deb ftp://ubuntu.realss.cn/ubuntu/ hardy main restricted universe multiversedeb ftp://ubuntu.realss.cn/ubuntu/ hardy-backports restricted universe multiversedeb ftp://ubuntu.realss.cn/ubuntu/ hardy-proposed main restricted universe multiversedeb ftp://ubuntu.realss.cn/ubuntu/ hardy-security main restricted universe multiversedeb ftp://ubuntu.realss.cn/ubuntu/ hardy-updates main restricted universe multiversedeb-src ftp://ubuntu.realss.cn/ubuntu/ hardy main restricted universe multiversedeb-src ftp://ubuntu.realss.cn/ubuntu/ hardy-backports main restricted universe multiversedeb-src ftp://ubuntu.realss.cn/ubuntu/ hardy-proposed main restricted universe multiversedeb-src ftp://ubuntu.realss.cn/ubuntu/ hardy-security main restricted universe multiversedeb-src ftp://ubuntu.realss.cn/ubuntu/ hardy-updates main restricted universe multiverse
LUPA软件源deb hardy main restricted universe multiversedeb hardy-security main restricted universe multiversedeb hardy-updates main restricted universe multiversedeb hardy-backports main restricted universe multiversedeb hardy-proposed main restricted universe multiversedeb-src hardy main restricted universe multiversedeb-src hardy-security main restricted universe multiversedeb-src hardy-updates main restricted universe multiversedeb-src hardy-backports main restricted universe multiversedeb-src hardy-proposed main restricted universe multiverse
2.浏览网速慢的问题
Firefox：网址栏输入about:config,在过滤器中输入IPv6，就会有一个是关于使用IPV6地址解析协议的，把它的Disable属性设为true即可（具体我也忘了，仔细看语义）
其它至于dns设定问题，我因为没有太多了解，，而且操作非常复杂，这里只提供一个下载文件。
祝你好运！
人要想成为生活的主人,不仅要适应生活,而且还要发挥主动性,
