近日使用centos6的伙伴会遇到yum源无法下载的问题，报错如下： Loading mirror speeds from cached hostfile YumRepo Error: All mirror URLs are not using ftp, http[s] or file. Eg. Invalid release/repo/arch combination/ removing mirrorlist with no valid mirrors: /var/cache/yum/x86_64/6/base/mirrorlist.