Spoke to the Customer Service of Dun And Bradstreet here in Singapore http://www.dnb.com.sg/db_duns_number.html and understand that it does not issue DUNs number for free since Feb 2016. New regsitration requires the sign up of DUNS Regsitered Seal which costs 400+ SGD.
With the seal you get the DUNS number.
The DUNS Seal can be renewed yearly for another 400+ SGD
While you can get a free (for normally slow service) DUNs, you'll have to pay 400+ for it here in Singapore.
Just thought I share this.