Is it possible to get a full list of all registered domain names in the world?
I have tried to look it up, but can not find any valid source.
Its okay if its a paid service.
No, it is not. That would require getting up-to-date and complete information from the registries for all the 1000+ top-level domains, and even if you were to go and ask all of them for it, some of them plain don't want you to know (like, for example, I'm guessing, .MIL).