The way I have mine set up, it will try another site if the first one fails. It's not set to use just one site.
Code:
[base]
name=Fedora Core $releasever - $basearch - Base
#baseurl=http://download.fedora.redhat.com/pub/fedora/linux/core/$releasever/$basearch/os/
mirrorlist=http://fedora.redhat.com/download/mirrors/fedora-core-$releasever
enabled=1
gpgcheck=1
[updates-released]
name=Fedora Core $releasever - $basearch - Released Updates
#baseurl=http://download.fedora.redhat.com/pub/fedora/linux/core/updates/$releasever/$basearch/
mirrorlist=http://fedora.redhat.com/download/mirrors/updates-released-fc$releasever
enabled=1
gpgcheck=1
[updates-testing]
name=Fedora Core $releasever - $basearch - Test Updates
#baseurl=http://download.fedora.redhat.com/pub/fedora/linux/core/updates/testing/$releasever/$basearch/
mirrorlist=http://fedora.redhat.com/download/mirrors/updates-testing-fc$releasever
enabled=0
gpgcheck=1
[development]
name=Fedora Core $releasever - Development Tree
#baseurl=http://download.fedora.redhat.com/pub/fedora/linux/core/development/$basearch/
mirrorlist=http://fedora.redhat.com/download/mirrors/fedora-core-rawhide
enabled=0