Clone SharePoint 2013 Production Farm as Test

I need to clone our production farm as test environment. Our system team cloned Frontend,Application and Database servers (virtual machines) and added domain with new server names. After that I did all things at the following link but configuration wizard still pointed to old (production) database server. What did I miss here??

http://www.meritsolutions.com/microsoft-sharepoint/cloning-sharepoint-2013-environment/

P.S. : Also link at this question is not working now Reconfiguring SharePoint 2010 Portal

Thanks in advance.