I generally recommend letting DNS handle this. The latest versions of the KRB client will default to resolving the KDC from SRV records in the DNS for the realm. This should be configured by default if you use Microsoft Active Directory (or AWS Simple AD).
If you want it explicit in your krb5.conf file, you can use DNS round robin with the A/AAA/CNAME and reference that name in krb5.conf. Further, you could have multiple "kdc" entries for a realm in krb5.conf and a master_kdc entry which is only used when there are certain kinds of issues.
You can always manage the krb5.conf from Ambari inside the Kerberos component configs.