Thanks for help. Now my client is accessable through http://hostname:port_no.
To do this, i have two options: either
--> disabled ASP.Net impersonation in IIS;
OR
--> In IIS -> DynamicsNAV (website) -> Physical Path Credentials setting.
supply 'Path credentials for Specific User' (domain user in my case)
From both above, WHICH IS BEST RECOMMENDED ???
and whenever i logged in through any of Active Directory accounts, i always got 'NAVADMIN' (my domain username) name as logged in user, Why so????