By default, yum deletes downloaded data files when they are no longer needed after a successful operation. This minimizes the amount of storage space that yum uses. However, you can enable caching, so that the package files downloaded by yum stay in cache directories. By using cached data, you can carry out certain operations without a network connection, you can also copy packages stored in the caches and reuse them elsewhere.
The yum cache will be automatically built up over time when you perform various yum queries such as installing or updating packages,. There is an option to manually make the cache so that future actions will be quicker with the ‘makecache’ argument. By adding the keyword fast to the end of the yum the makecache command will make it populate the yum cache even faster but will end up caching fewer repositories
