1、先查DNS
先测试公共 IP 连通性(确保网络能出外网)
ping -c 4 223.5.5.5如果联不通则考虑重新配置DNS
# 备份原有配置 cp /etc/resolv.conf /etc/resolv.conf.bak # 清空并写入可靠公共DNS echo "nameserver 223.5.5.5" > /etc/resolv.conf echo "nameserver 8.8.8.8" >> /etc/resolv.conf echo "nameserver 114.114.114.114" >> /etc/resolv.conf # 临时锁定文件,防止被系统自动覆盖 chattr +i /etc/resolv.conf #后续yum没问题之后可解锁/etc/resolv.conf(允许系统自动修改 DNS): chattr -i /etc/resolv.conf验证域名解析是否成功
# 测试解析阿里云镜像域名 nslookup mirrors.aliyun.com2、配置yum镜像
# 1. 进入yum仓库配置目录 cd /etc/yum.repos.d/ # 2. 备份所有原有repo文件(创建backup目录,移动所有.repo文件进去) mkdir -p backup && mv *.repo backup/ # 3. 下载阿里云的CentOS 7镜像源(wget直接下载,无需依赖yum) wget -O CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-7.repo # 4. 下载epel镜像源(阿里云的epel源,对应CentOS 7) wget -O epel.repo https://mirrors.aliyun.com/repo/epel-7.repo # 5. 清理原有yum缓存,生成新的缓存(此时镜像源已有效,yum可正常工作) yum clean all yum makecache fast如果提示wget: command not found,说明系统没有安装 wget,先手动下载 wget rpm 包安装:
# 下载wget for CentOS 7 curl -O https://mirrors.aliyun.com/centos/7/os/x86_64/Packages/wget-1.14-18.el7_6.1.x86_64.rpm # 本地安装wget(无依赖,直接rpm安装) rpm -ivh wget-1.14-18.el7_6.1.x86_64.rpm