The default file is the file shown when someone visits your domain name or sub directory without specifying the file name.
No File Name Specified
Example: http://www.miskdomain.com/
Example: http://www.miskdomain.com/subdir/
File Name Specified
Example: http://www.miskdomain.com/index.html
Example: http://www.miskdomain.com/subdir/index.html
When no file name is specified, like in the first examples, we search for and show the default file in the order shown below.
When you first enable Web Hosting, we place a standard index.html file in your ftp directory as your initial default file so visitors know you're building your web site.
You must use one of the following file names as your default file
index.html
index.htm
default.html
default.htm
The default files are looked up in the above order from top to bottom
So, if you had both a index.html and default.html file in your FTP folder, index.html would always be served as the default file. To have default.html shown as the default file, you would need to delete the index.html file since it is higher in the default file order above.