dnf.conf に fastestmirror=1 を指定する
/etc/dnf/dnf.conf
[main]
gpgcheck=True
installonly_limit=3
clean_requirements_on_remove=True
best=False
skip_if_unavailable=True
fastestmirror=1
参考サイト
https://darryldias.me/2020/how-to-setup-fastest-mirror-in-dnf/
https://dnf.readthedocs.io/en/latest/conf_ref.html
dnf.conf に proxy=proxy.example.com:3128 を指定する
/etc/dnf/dnf.conf
[main]
gpgcheck=True
installonly_limit=3
clean_requirements_on_remove=True
best=False
skip_if_unavailable=True
proxy=proxy.example.com:3128