Now, it is important to realize that in many instances, the general cause of an error with Yum can begin with the network environment, an issue related to disk space, mixed repositories, or even the DNS settings on the system. However, there are occasions when a few common procedural errors will need rectifying by flushing Yum itself with one or more of the following range of commands.

To purge old package information, you should use:

# yum clean headers

To clean all cached packages, use the following command:

# yum clean packages

To clean all cached XML-based data, use this:

# yum clean metadata

However, if you would like to flush the Yum cache in its entirety (including all headers, metadata, download packages, and more), you can always use the following command to complete the process:

# yum clean all