i am using wordpress MU Domain mapping plugin and also configuration same as they provide guide how to configuration on server. first i created sub-folder multisite network on server then after create the one new site like site name is 'site1' so url created like this "htttp://example.com/site1". this one was worked fine but when i created one subdomain on my server like "http://site1/example.com" and this one set on domainmapping setting in site1 admin panel. but when i clicked on visit site then its not working and display the "The page isn't redirecting properly". so anyone help me how to WordPress MU Domain mapping working and how to configuration on sever.