ubuntu 15.10 更新源和apt-get update失败的解决方案

今晚利用Software & Updates工具更新源时总是出现Failed to download repository information这个错误，解决方案如下：

sudo gedit /etc/apt/source.list

然后把旧的源的命令都注释掉，再添加https://blog.csdn.net/paincupid/article/details/52895676中所列的任何一个源。

我用的是清华大学的，具体如下：

deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial main restricted
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-updates main restricted
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial universe
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-updates universe
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial multiverse
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-updates multiverse
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security main restricted
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security universe

deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security multiverse

然后使用sudo apt-get update更新一下，但是我又遇到update失败，错误有：

E: Failed to fetch http://cn.archive.ubuntu.com/ubuntu/dists/willy-proposed/restricted/binary-i386/Packages  404  Not Found [IP: 91.189.91.26 80]

……

E: Some index files failed to download, they have been ignored, or old ones used instead.

解决方法如下：

sudo gedit /etc/resolv.conf

修改dns配置如下：

search localdomain
nameserver 202.96.128.86 

nameserver 202.96.128.166 

重启网络：sudo /etc/init.d/networking restart。

希望对大家有帮助。