http://mirrors.aliyun.com/centos/7.2.1511/os/x86_64/Packages/
http://mirrors.aliyun.com/centos/7.2.1511/extras/x86_64/Packages/
当mirror失效后用
http://vault.centos.org/centos/7.2.1511/extras/x86_64/Packages/
http://vault.centos.org/7.2.1511/os/x86_64/Packages/
原文：http://www.cnblogs.com/itzxy/p/6549941.html