The module is doing the same discovery that ipa-client-install is doing
internally. The results are saved into a structure named ipadiscovery for
the ansible module.

The discovery module is needed to be able to not depend on the definition
of the ipaservers group for example to get otp passwords, to be able to
join and to configure sssd and other services corretly.

More than one server could be specified

node and the credential cache is copied to the managed node

ipahost module is also using facts gathered from the server to find the
domain and realm.