Suggested solution: At the end of ipa-replica-prepare, wait until the replica's hostname is resolvable. Say "this check may be safely interrupted if the DNS record will be added later". Add an option (--no-wait-for-dns) to skip the wait.

Please note that this is useful even for installations where DNS is managed outside of IPA.
It:

• reminds admin to add the new record
• checks that admin did the right thing

master:

• ffe4417 ipa-replica-prepare: Wait for the DNS entry to be resolvable

ipa-4-1:

• ee4a023 ipa-replica-prepare: Wait for the DNS entry to be resolvable

ipa-4-0:

• 1794237 ipa-replica-prepare: Wait for the DNS entry to be resolvable