这2周做实验,centos7.x经常出现yum安装软件包的时候找不到解析地址,提示如下错误 正在尝试其它镜像. Error downloading packages: pam-devel-1.1.8-22.el7.x86_64: [Errno 256] No more mirrors to try. libcom_err-1.42.9-12.el7_5.x86_64: [Errno 256] No more mirrors to try. keyutils-libs-devel-1.5.8-3.