When creating a realm, you have the option to enable "Realm Alias Referrals" in "Configuration - Global - Policy Configuration". This will use the DNS alias for the realm to set uo referrals as an automatic process. Using the internal configuration store, these referrals are updated to reflect a change in DNS alias, but when using an external configuration store, this is not updated until OpenAM is restarted.
Steps to reproduce:
Set up a realm with a DNS alias configured, and enable Realm Alias referrals. Verify that the referral for the realm reflects the DNS name, by adding a URL policy, which will display the referral DNS name for this policy. Then change the DNS alias for the realm, and perform the same policy configuration, and you will see the referral has not been updated.