32Bit :
echo "https://vault.centos.org/6.10/os/i386/" > /var/cache/yum/i386/6/base/mirrorlist.txt
echo "http://vault.centos.org/6.10/extras/i386/" > /var/cache/yum/i386/6/extras/mirrorlist.txt
echo "http://vault.centos.org/6.10/updates/i386/" > /var/cache/yum/i386/6/updates/mirrorlist.txt
64Bit :
echo "https://vault.centos.org/6.10/os/x86_64/" > /var/cache/yum/x86_64/6/base/mirrorlist.txt
echo "http://vault.centos.org/6.10/extras/x86_64/" > /var/cache/yum/x86_64/6/extras/mirrorlist.txt
echo "http://vault.centos.org/6.10/updates/x86_64/" > /var/cache/yum/x86_64/6/updates/mirrorlist.txt
출처 : CentOS 6 yum update 오류해결 (Feat, YumRepo Error: All mirror URLs are not using ftp, http[s] or file) :: 복싱과 IT의 공생 (tistory.com)