CentOS 7 and CentOS 8 updated repo after its EOL

For CentOS 7

mirrorlist.centos.org doesn’t exists anymore. So, your default repor wwith yum doesn’t work. Try using the following processes, it worked for me, hope this works for others as well.

sed -i s/mirror.centos.org/vault.centos.org/g /etc/yum.repos.d/*.repo
sed -i s/^#.*baseurl=http/baseurl=http/g /etc/yum.repos.d/*.repo
sed -i s/^mirrorlist=http/#mirrorlist=http/g /etc/yum.repos.d/*.repo

Ref:
https://serverfault.com/questions/1161816/mirrorlist-centos-org-no-longer-resolve

For CentOS 8

sed -i 's/^mirrorlist/#mirrorlist/g' /etc/yum.repos.d/CentOS-*
sed -i 's|#baseurl=http://mirror.centos.org|baseurl=http://vault.centos.org|g' /etc/yum.repos.d/CentOS-*