Prior to Fedora 7, all of the "core" distribution for Fedora and other Red Hat-based distributions would fit on a small number of CDs or a single DVD. This made it easy to download the ISO image(s) for the distribution and use them as a local repository for multiple machines on the same network, as described in YumRepoFromImages.
Similarly, it was possible to mirror the update repository for the "core" distribution and use that as a local mirror for the network.
Fedora Core 3 introduced the community-based Extras repository, which by the time of Fedora Core 6 had become much bigger than the base distribution itself. This too could be mirrored locally, but it ate up a lot of disk space and bandwidth, and in many cases it wasn't worth doing because the packages in Extras weren't as commonly used and so it made more sense to download them from the Internet as and when needed.
From Fedora 7, the Core and Extras repositories were merged, and the distribution media became only a subset of the whole distribution. Using a DVD ISO as a replacement for the main repository was no longer possible because it would not make all packages available. Similarly, the "updates" repository included packages that were previously in Extras, making it much bigger than it was in earlier distribution releases.
This article describes a way of maintaining and using local mirrors of the most common packages (those on the media) and their updates, whilst still having access to the other packages via the Internet. It is based on using the standard yum-based tools and should work with all yum-based package management tools such as pirut and yumex.
The means by which local repositories can be used was considerably simplified in Fedora 8, so there are now separate pages for Fedora 7 onwards in order to maintain clarity: