[Yum] Downloading header problems

[Lasaro]

Please,

    I need help the error below, any help?

Setting up Update Process
Setting up Repos
http://download.fedora.redhat.com/pub/fedora/linux/core/3/i386/os/repodata/repomd.xml:
[Errno 4] IOError: <urlopen error (-2, 'Name or service not known')>
Trying other mirror.
Cannot open/read repomd.xml file for repository: base
failure: repodata/repomd.xml from base: [Errno 256] No more mirrors to try.