IPA is an identity solution stack, of which the following is included:
LDAP Kerberos NTP DNS
Red Hat Directory Server is just a LDAP implementation - which, incidentally, is based on Fedora 389 Directory Server, which, in turn, is included in IPA.
https://docs.fedoraproject.org/en-US/Fedora/18/html/FreeIPA_Guide/Configuring_an_IPA_Client_on_AIX.html
https://www.freeipa.org/page/SUDO_Integration_for_AIX
https://www.server-world.info/en/note?os=CentOS_7&p=ipa