CENTOS7にFFMPEGをインストールしようとすると、ミラーが見つかりません。

私はrootアクセス権を持つ専用サーバーを使用しています。サーバーに慣れていません。私のサーバーにFFMpegをインストールしようとしています。エラーが発生しましたが、解決策がわかりません。したがって、これに対する洞察力は大変感謝いたします。

[root@ns335004 ~]# yum update
base                                                                                                           | 3.6 kB  00:00:00     
http://apt.sw.be/redhat/el7/en/x86_64/dag/repodata/repomd.xml: [Errno 14] HTTP Error 404 - Not Found
Trying other mirror.
To address this issue please refer to the below knowledge base article 

https://access.redhat.com/articles/1320623

If above article doesn't help to resolve this issue please create a bug on https://bugs.centos.org/



 One of the configured repositories failed (DAG RPM Repository),
 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. Disable the repository, 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 dag

     4. 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=dag.skip_if_unavailable=true

failure: repodata/repomd.xml from dag: [Errno 256] No more mirrors to try.
http://apt.sw.be/redhat/el7/en/x86_64/dag/repodata/repomd.xml: [Errno 14] HTTP Error 404 - Not Found

再研磨

[root@ns335004 ~]# yum repolist all
http://apt.sw.be/redhat/el7/en/x86_64/dag/repodata/repomd.xml: [Errno 14] HTTP Error 404 - Not Found
Trying other mirror.
To address this issue please refer to the below knowledge base article 

https://access.redhat.com/articles/1320623

If above article doesn't help to resolve this issue please create a bug on https://bugs.centos.org/

http://apt.sw.be/redhat/el7/en/x86_64/dag/repodata/repomd.xml: [Errno 14] HTTP Error 404 - Not Found
Trying other mirror.
repo id                                  repo name                                                                     status
C7.0.1406-base/x86_64                    CentOS-7.0.1406 - Base                                                        disabled
C7.0.1406-centosplus/x86_64              CentOS-7.0.1406 - CentOSPlus                                                  disabled
C7.0.1406-extras/x86_64                  CentOS-7.0.1406 - Extras                                                      disabled
C7.0.1406-fasttrack/x86_64               CentOS-7.0.1406 - CentOSPlus                                                  disabled
C7.0.1406-updates/x86_64                 CentOS-7.0.1406 - Updates                                                     disabled
C7.1.1503-base/x86_64                    CentOS-7.1.1503 - Base                                                        disabled
C7.1.1503-centosplus/x86_64              CentOS-7.1.1503 - CentOSPlus                                                  disabled
C7.1.1503-extras/x86_64                  CentOS-7.1.1503 - Extras                                                      disabled
C7.1.1503-fasttrack/x86_64               CentOS-7.1.1503 - CentOSPlus                                                  disabled
C7.1.1503-updates/x86_64                 CentOS-7.1.1503 - Updates                                                     disabled
base/7/x86_64                            CentOS-7 - Base                                                               enabled:  9,007
base-debuginfo/x86_64                    CentOS-7 - Debuginfo                                                          disabled
base-source/7                            CentOS-7 - Base Sources                                                       disabled
c7-media                                 CentOS-7 - Media                                                              disabled
centosplus/7/x86_64                      CentOS-7 - Plus                                                               disabled
centosplus-source/7                      CentOS-7 - Plus Sources                                                       disabled
cr/7/x86_64                              CentOS-7 - cr                                                                 disabled
dag/7/x86_64                             DAG RPM Repository                                                            enabled:      0
epel/x86_64                              Extra Packages for Enterprise Linux 7 - x86_64                                enabled: 10,764
epel-debuginfo/x86_64                    Extra Packages for Enterprise Linux 7 - x86_64 - Debug                        disabled
epel-source/x86_64                       Extra Packages for Enterprise Linux 7 - x86_64 - Source                       disabled
epel-testing/x86_64                      Extra Packages for Enterprise Linux 7 - Testing - x86_64                      disabled
epel-testing-debuginfo/x86_64            Extra Packages for Enterprise Linux 7 - Testing - x86_64 - Debug              disabled
epel-testing-source/x86_64               Extra Packages for Enterprise Linux 7 - Testing - x86_64 - Source             disabled
extras/7/x86_64                          CentOS-7 - Extras                                                             enabled:    393
extras-source/7                          CentOS-7 - Extras Sources                                                     disabled
fasttrack/7/x86_64                       CentOS-7 - fasttrack                                                          disabled
nux-dextop/x86_64                        Nux.Ro RPMs for general desktop use                                           disabled
nux-dextop-testing/x86_64                Nux.Ro RPMs for general desktop use - testing                                 disabled
plesk-php-5.6                            PHP v 5.6 for Plesk - x86_64                                                  enabled:     31
plesk-php-7.0                            PHP v 7.0 for Plesk - x86_64                                                  enabled:     28
updates/7/x86_64                         CentOS-7 - Updates                                                            enabled:  2,560
updates-source/7                         CentOS-7 - Updates Sources                                                    disabled
repolist: 22,783

私も次のことを試しました。

sudo yum clean metadata
sudo yum clean all

しかし、まだ同じ404エラーが発生します。

ありがとうございます。