Source
SYSTEM$GET_SERVICE_DNS_DOMAIN
This is the same DNS domain that appears in the DNS name (as reported by SHOW SERVICES) for any service in the DATA_SCHEMA schema.
SHOW SERVICES and DESCRIBE SERVICE commands: New format for the DNS name of a service
…unique - id replaces the schema - name.db - name and is a 4 - 8 character long alphanumeric identifier that is unique to a particular instance of a database schema. To find the unique ID for a schema, call the SYSTEM$GET_SERVICE_DNS_DOMAIN…