Some index files failed to download. They have …… or old ones used instead

問題：

平台：Ubuntu12.04

W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/universe/binary-i386/Packages 404 Not Found [IP: 91.189.92.182 80]
E: Some index files failed to download. They have been ignored, or old ones used instead. 

分析：

在安裝系統的時候，代理服務器填寫錯誤。 

解決：

創建或編輯/etc/apt/apt.conf文件

sudo vi /etc/apt/apt.conf
    添加如下內容：
    Acquire::http { Proxy "http://192.168.88.10:3142"; }; 
    或
    Acquire::http::Proxy "http://192.168.88.10:3142";  

注：代理服務器可不填寫，即把該文件清空；代理服務器填寫請根據實際情況填寫，以上為本人的個人情況而已。