Centos7 yum阿里源报错Failed connect to mirrors aliyuncs com80 拒绝连接

报错记录：

原因是由于非阿里云ECS用户无法解析主机“mirrors.cloud.aliyuncs.com”，只需将CentOS-Base里包含aliyuncs.com的行删除即可。

# 1、备份原来源
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup
# 2、下载阿里源
wget -O /etc/yum.repos.d/CentOS-Base.repo [http://mirrors.aliyun.com/repo/Centos-7.repo](https://links.jianshu.com/go?to=http%3A%2F%2Fmirrors.aliyun.com%2Frepo%2FCentos-7.repo)
# 3、替换源地址
sed -i -e '/mirrors.cloud.aliyuncs.com/d' -e '/mirrors.aliyuncs.com/d' /etc/yum.repos.d/CentOS-Base.repo
# 4、刷新缓存
yum makecache
# 5、更新
yum -y update