Yum update was not working found this
as of July 1 repos url changed to VAULT archive repositories
Had to change Centos-Base.repo with following command:
vi /etc/yum.repos.d/CentOS-Base.repo
---------------then SNIP image of current config for safe keeping incase.
In file Replace everything under [base]
[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
I followed this guide and got my YUM update to work with new URLs:
https://serverfault.com/questions/904304/could-not-resolve-host-mirrorlist-centos-org-centos-7