系统版本：

cat /etc/centos-release

CentOS Linux release 7.9.2009 (Core)

一、CentOS7 CentOS-Base.repo 阿里云镜像

cp /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.bak

vi /etc/yum.repos.d/CentOS-Base.repo

<code># 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 - mirrors.aliyun.com

failovermethod=priority

baseurl=http://mirrors.aliyun.com/centos/$releasever/os/$basearch/

http://mirrors.aliyuncs.com/centos/$releasever/os/$basearch/

http://mirrors.cloud.aliyuncs.com/centos/$releasever/os/$basearch/

gpgcheck=1

gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

#released updates

[updates]

name=CentOS-$releasever - Updates - mirrors.aliyun.com

failovermethod=priority

baseurl=http://mirrors.aliyun.com/centos/$releasever/updates/$basearch/

http://mirrors.aliyuncs.com/centos/$releasever/updates/$basearch/

http://mirrors.cloud.aliyuncs.com/centos/$releasever/updates/$basearch/

gpgcheck=1

gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

#additional packages that may be useful

[extras]

name=CentOS-$releasever - Extras - mirrors.aliyun.com

failovermethod=priority

baseurl=http://mirrors.aliyun.com/centos/$releasever/extras/$basearch/

http://mirrors.aliyuncs.com/centos/$releasever/extras/$basearch/

http://mirrors.cloud.aliyuncs.com/centos/$releasever/extras/$basearch/

gpgcheck=1

gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

#additional packages that extend functionality of existing packages

[centosplus]

name=CentOS-$releasever - Plus - mirrors.aliyun.com

failovermethod=priority

baseurl=http://mirrors.aliyun.com/centos/$releasever/centosplus/$basearch/

http://mirrors.aliyuncs.com/centos/$releasever/centosplus/$basearch/

http://mirrors.cloud.aliyuncs.com/centos/$releasever/centosplus/$basearch/

gpgcheck=1

enabled=0

gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

#contrib - packages by Centos Users

[contrib]

name=CentOS-$releasever - Contrib - mirrors.aliyun.com

failovermethod=priority

baseurl=http://mirrors.aliyun.com/centos/$releasever/contrib/$basearch/

http://mirrors.aliyuncs.com/centos/$releasever/contrib/$basearch/

http://mirrors.cloud.aliyuncs.com/centos/$releasever/contrib/$basearch/

gpgcheck=1

enabled=0

gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

二、CentOS-Base.repo原始文件

# 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/

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/

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/

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/

gpgcheck=1

enabled=0

gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

三、使用阿里云镜像之前的报错

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"

[root@localhost ~]# telnet 172.172.172.172 3306

-bash: telnet: 未找到命令

[root@localhost ~]# rpm -qa telnet

[root@localhost ~]# yum install telnet

已加载插件：fastestmirror

Loading mirror speeds from cached hostfile

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"

One of the configured repositories failed (未知),

and yum doesn't have enough cached data to continue. At this point the only

safe thing yum can do is fail. There are a few ways to work "fix" this:

1. Contact the upstream for the repository and get them to fix the problem.

2. Reconfigure the baseurl/etc. for the repository, to point to a working

upstream. This is most often useful if you are using a newer

distribution release than is supported by the repository (and the

packages for the previous distribution release still work).

3. Run the command with the repository temporarily disabled

yum --disablerepo=<repoid> ...

4. Disable the repository permanently, so yum won't use it by default. Yum

will then just ignore the repository until you permanently enable it

again or use --enablerepo for temporary usage:

yum-config-manager --disable <repoid>

or

subscription-manager repos --disable=<repoid>

5. Configure the failing repository to be skipped, if it is unavailable.

Note that yum will try to contact the repo. when it runs most commands,

so will have to try and fail each time (and thus. yum will be be much

slower). If it is a very temporary problem though, this is often a nice

compromise:

yum-config-manager --save --setopt=<repoid>.skip_if_unavailable=true

Cannot find a valid baseurl for repo: base/7/x86_64

四、参考命令

yum clean all

yum makecache

yum update

Is this ok [y/d/N]: N

y：下载安装，d：只下载不安装，N：不安装

参考：

centos6&7&8搭建私有仓库_centos-base.repo