问题报错
使用yum安装软件时出现以下错误：
[root@p52q3sxp ~]# yum install python-setuptools
已加载插件：fastestmirror
Determining fastest mirrors
Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=os&infra=stock error was
14: curl#6 - "Could not resolve host: mirrorlist.centos.org; 未知的错误"问题原因
出现这个错误是因为使用的 CentOS 7 仓库已经被归档，当前的镜像地址无法找到所需的文件。CentOS 7 的官方支持已经结束，部分仓库已被移至归档库。这导致了你的 yum 命令无法找到所需的元数据文件。CentOS 7 的官方仓库在 2024 年 6 月 30 日之后已经停止维护。因此，使用最新的 CentOS 7 官方仓库可能会遇到问题。
解决方法（官方源）
# 进入yum源仓库
[root@p52q3sxp ~]# cd /etc/yum.repos.d/
[root@p52q3sxp yum.repos.d]# ls
CentOS-Base.repo CentOS-Debuginfo.repo CentOS-Media.repo CentOS-Vault.repo
CentOS-CR.repo CentOS-fasttrack.repo CentOS-Sources.repo CentOS-x86_64-kernel.repo
# 备份CentOS-Base.repo文件，修改文件
[root@p52q3sxp yum.repos.d]# cp CentOS-Base.repo CentOS-Base.repo.bak
[root@p52q3sxp yum.repos.d]# vi CentOS-Base.repo将CentOS-Base.repo文件修改为以下内容
# CentOS-Base.repo
#
# The mirror system uses the connecting IP address of the client and the
# update status of each mirror to pick mirrors that are updated to and
# geographically close to the client. You should use this for CentOS updates
# unless you are manually picking other mirrors.
#
# If the mirrorlist= does not work for you, as a fall back you can try the
# remarked out baseurl= line instead.
#
#
[base]
name=CentOS-$releasever - Base
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os&infra=$infra
#baseurl=http://mirror.centos.org/centos/$releasever/os/$basearch/
#baseurl=http://vault.centos.org/7.9.2009/x86_64/os/
baseurl=http://vault.centos.org/7.9.2009/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
#released updates
[updates]
name=CentOS-$releasever - Updates
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates&infra=$infra
#baseurl=http://mirror.centos.org/centos/$releasever/updates/$basearch/
#baseurl=http://vault.centos.org/7.9.2009/x86_64/os/
baseurl=http://vault.centos.org/7.9.2009/updates/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
#additional packages that may be useful
[extras]
name=CentOS-$releasever - Extras
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras&infra=$infra
#$baseurl=http://mirror.centos.org/centos/$releasever/extras/$basearch/
#baseurl=http://vault.centos.org/7.9.2009/x86_64/os/
baseurl=http://vault.centos.org/7.9.2009/extras/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$releasever - Plus
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus&infra=$infra
#baseurl=http://mirror.centos.org/centos/$releasever/centosplus/$basearch/
#baseurl=http://vault.centos.org/7.9.2009/x86_64/os/
baseurl=http://vault.centos.org/7.9.2009/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7清理缓存并重新缓存
[root@p52q3sxp yum.repos.d]# yum clean all
已加载插件：fastestmirror
正在清理软件源： base extras updates
Cleaning up list of fastest mirrors
[root@p52q3sxp yum.repos.d]# yum makecache
已加载插件：fastestmirror
Determining fastest mirrors
base
···················
元数据缓存已建立解决方案（阿里源）
如果想要使用阿里源，使用以下方法
# 以下两个命令都可以
curl -o /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-7.repo
wget -O /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-7.repo
# 清理缓存并重新建立元数据缓存
[root@p52q3sxp yum.repos.d]# yum clean all
已加载插件：fastestmirror
正在清理软件源： base extras updates
Cleaning up list of fastest mirrors
[root@p52q3sxp yum.repos.d]# yum makecache
已加载插件：fastestmirror
Determining fastest mirrors
base
···················
元数据缓存已建立
