At the beginning, this blog use address hostingformula.info and because I use bluehost I have free domain hostingformula.net . The transition from .info to .net is smooth with help of permanent redirect 301 .
Old domain no longer work since its expired and wordpress stats tell me with this data :
Sure, 301 redirect only work if old domain and new domain are active. If one of them no longer work then I must doing something to overcome this issue.
After think for a while I decide to replace old link that might be linked manually with new link.