What is the Django HOST_DOMAIN setting for?
That is not a Django setting.
It's perfectly good practice to define your own project-specific settings inside settings.py, and that is presumably what the original developer did here.
Despite googling I can't find any documentation for the Django HOST_DOMAIN setting in the settings.py.
I am going through a settings.py file I have been given and this is the only part of the file I am not 100% clear on.