Yes, we can run an asp.net application without the WEB.CONFIG file.
If we are not setting any configuration in WEB.CONFIG file then it will take MACHINE.CONFIG file for default configurations. This config file will automatically installed when your application getting executed.
i.e MACHINE.CONFIG file contains defaults settings for all the asp.net web applications.
Because all the configuration settings will be available under MACHINE.CONFIG file by default these settings will be applied to all asp.net applications. The MACHINE.CONFIG file will be automitacally loaded when .net framework is installed.
it is something like if we had not defined the web.config the application will take the settings from the machine.config.the machine.config settings are overide by the web.config if u define the web.config for each running appln
In 2005 The VS When we trying to run first time any application the 2005 VS gives us warning that want to run application without beb.config file.