DASH encoders can upload the mpd file just once (as per the standard) or at an arbitrary interval that they choose.

However, check that the mpd file is not uploaded too frequently or too late. An update interval of about 30 seconds is ideal.

The content of the file might or might not change on each upload.

The URL format is: http://{hostname}/{format}/{streamID}/{eventname}/{anyname}.mpd

For example: