Could not resolve host: mirrorlist.centos.org Centos 7 when using "yum update"

 Could not resolve host: mirrorlist.centos.org Centos 7 when using "yum update"

I have a fresh install of centos 7.

[root@localhost ~]# cat /etc/centos-release
CentOS Linux release 7.4.1708 (Core) 
[root@localhost ~]# 

When I tried to update with yum, I saw that yum is giving error.

[root@localhost ~]# yum update
Loaded plugins: fastestmirror
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; Unknown error"
http://mirror.centos.org/centos/7/os/x86_64/repodata/repomd.xml: [Errno 14] curl#6 - "Could not resolve host: mirror.centos.org; Unknown error"
Trying other mirror.

 One of the configured repositories failed (CentOS-7 - Base),
 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=base ...

     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 base
        or
            subscription-manager repos --disable=base

     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=base.skip_if_unavailable=true

failure: repodata/repomd.xml from base: [Errno 256] No more mirrors to try.
http://mirror.centos.org/centos/7/os/x86_64/repodata/repomd.xml: [Errno 14] curl#6 - "Could not resolve host: mirror.centos.org; Unknown error"
[root@localhost ~]# 

So when I list the repos I get this:

[root@localhost ~]# yum repolist all
Loaded plugins: fastestmirror
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; Unknown error"
http://mirror.centos.org/centos/7/os/x86_64/repodata/repomd.xml: [Errno 14] curl#6 - "Could not resolve host: mirror.centos.org; Unknown error"
Trying other mirror.
http://mirror.centos.org/centos/7/os/x86_64/repodata/repomd.xml: [Errno 14] curl#6 - "Could not resolve host: mirror.centos.org; Unknown error"
Trying other mirror.
Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=centosplus&infra=stock error was
14: curl#6 - "Could not resolve host: mirrorlist.centos.org; Unknown error"
http://mirror.centos.org/centos/7/centosplus/x86_64/repodata/repomd.xml: [Errno 14] curl#6 - "Could not resolve host: mirror.centos.org; Unknown error"
Trying other mirror.
Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=extras&infra=stock error was
14: curl#6 - "Could not resolve host: mirrorlist.centos.org; Unknown error"
http://mirror.centos.org/centos/7/extras/x86_64/repodata/repomd.xml: [Errno 14] curl#6 - "Could not resolve host: mirror.centos.org; Unknown error"
Trying other mirror.
Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=updates&infra=stock error was
14: curl#6 - "Could not resolve host: mirrorlist.centos.org; Unknown error"
http://mirror.centos.org/centos/7/updates/x86_64/repodata/repomd.xml: [Errno 14] curl#6 - "Could not resolve host: mirror.centos.org; Unknown error"
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
:
updates-source/7                                                                                CentOS-7 - Updates Sources                                                                        disabled
repolist: 0
[root@localhost ~]# 

Show the current /etc/yum.repos.d/CentOS-Base.repo.

# 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=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

• 
  

  Solution:

  1. Check DNS server 

  - Try using ping 8.8.8.8. If this fails, try ping <local-gateway-ip>. If that also fails, your local network configuration is wrong and you'll have to check the configuration.

     # ping 8.8.8.8 

  - Check your DNS setting, /etc/resolv.conf to see what's configured.

  - Test your DNS setting
    # nslookup google.com
    or
    # dig google.com

  If DNS work fine, do the next step. If fail, you need to check your DNS setting.

• 2.  Use browser to  look up mirrorlist.centos.org. Found that it can not open this url.

  3. From first of July 2024 on CentOS 7, please switch to Vault archive repositories:

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

  copy/paste the following and mind your OS version. Change if needed. In this config is version 7.9.2009:

  [base]
  name=CentOS-$releasever - Base
  baseurl=http://vault.centos.org/7.9.2009/os/$basearch/
  gpgcheck=1
  gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
  
  [updates]
  name=CentOS-$releasever - Updates
  baseurl=http://vault.centos.org/7.9.2009/updates/$basearch/
  gpgcheck=1
  gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
  
  [extras]
  name=CentOS-$releasever - Extras
  baseurl=http://vault.centos.org/7.9.2009/extras/$basearch/
  gpgcheck=1
  gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
  
  [centosplus]
  name=CentOS-$releasever - Plus
  baseurl=http://vault.centos.org/7.9.2009/centosplus/$basearch/
  gpgcheck=1
  enabled=0
  gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

  • Note: Refer to https://blog.centos.org/2023/04/end-dates-are-coming-for-centos-stream-8-and-centos-linux-7/ For CentOS End of Life.
    
  
  After that, try to run "yum update" again.

• • Now everything work fine.
    
• 
  
  
•