If you get this error message when trying to update the system (see example below) or just pinging an external host …
$> sudo pacman -Syu :: Synchronizing package databases... error: failed retrieving file 'core.db' from mirror.archlinuxarm.org : Could not resolve host: mirror.archlinuxarm.org error: failed to update core (download library error) error: failed retrieving file 'extra.db' from mirror.archlinuxarm.org : Could not resolve host: mirror.archlinuxarm.org error: failed to update extra (download library error) error: failed retrieving file 'community.db' from mirror.archlinuxarm.org : Could not resolve host: mirror.archlinuxarm.org error: failed to update community (download library error) error: failed retrieving file 'alarm.db' from mirror.archlinuxarm.org : Could not resolve host: mirror.archlinuxarm.org error: failed to update alarm (download library error) error: failed retrieving file 'aur.db' from mirror.archlinuxarm.org : Could not resolve host: mirror.archlinuxarm.org error: failed to update aur (download library error) error: failed to synchronize any databases error: failed to init transaction (download library error)
… you have to declare an default route:
$> sudo ip route add default via 192.168.178.1