Failed to fetch http://mirrors.cloud.aliyuncs.com/

服務器版本：阿里雲 ubuntu 16.04

問題：
阿里雲安裝軟件時，提示

W: Failed to fetch http://mirrors.cloud.aliyuncs.com/ubuntu/dists/xenial/InRelea                                                 se  Could not resolve 'mirrors.cloud.aliyuncs.com'
W: Failed to fetch http://mirrors.cloud.aliyuncs.com/ubuntu/dists/xenial-updates                                                 /InRelease  Could not resolve 'mirrors.cloud.aliyuncs.com'
W: Failed to fetch http://mirrors.cloud.aliyuncs.com/ubuntu/dists/xenial-securit                                                 y/InRelease  Could not resolve 'mirrors.cloud.aliyuncs.com'
W: Some index files failed to download. They have been ignored, or old ones used                                                  instead.

先給出正確的解決方案，再告訴你們，我怎麼分析的

cd /etc/apt/sources.list.d
 cp sources-aliyun-0.list sources-aliyun-0.list.bak   # 保留原版本以防改錯

將 sources-aliyun-0.list 內的內容替換成如下內容

deb http://mirrors.aliyun.com/ubuntu/ xenial main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse
##測試版源
deb http://mirrors.aliyun.com/ubuntu/ xenial-proposed main restricted universe multiverse
# 源碼
deb-src http://mirrors.aliyun.com/ubuntu/ xenial main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse
##測試版源
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-proposed main restricted universe multiverse
# Canonical 合做夥伴和附加
deb http://archive.canonical.com/ubuntu/ xenial partner

修改完畢執行

apt-get update  # 更新源

到此，問題解決。

回顧解決過程
一、從百度和goole尚搜索，大多指向的是dns解析問題。
好比讓我修改 dns 配置文件

vim /etc/resolvconf/resolv.conf.d/base

增長 2個dns解析

nameserver 8.8.8.8
nameserver 8.8.4.4

修改完畢後，執行命令

resolvconf -u

添加了dns 其實仍是不行，緣由就是，錯誤提示的網址根本無法訪問。

知道了問題出在哪裏，那咱們就能夠根據問題來解決
二、百度搜索 阿里雲更換 apt-get 源。 搜索後，就出現了，文章開頭的解決方案啦！