Enter а domain name for which you are performing the verification of а robots.txt file. Do not append the trailing '/robots.txt' or '/' to the domain name. By default Moderatobot uses 'http' protocol and 80 port to access your domain. So you need to specify the protocol or/and port only if you use another ones.
Some examples of correct domain names:
Just change the mode by clicking the "Settings" button if you want to check the file in different conditions.