Sometimes when running yum check-update on a CentOS system, yum will complain about a particular repomd.xml file being out of date. You might see output like this:
[[email protected] ~]# yum check-update
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
MySQL and MariaDB have been diverging since 2010, and now they should be considered different software products (sort of like Microsoft SQL server vs. Sybase). You should tell us which one you use, and tag your question appropriately. The answer to your question will be different depending on...