What is a domain server?

I’ve been looking around and I’m struggling to discover if a domain server is different than a domain name server, which I understand to be a server that maps URL names to IP addresses.

Are these two things different? Is it a different shorthand for DNS?

To add context to this question: I have a question on a code questionnaire that I got from a company as a prequel to a technical interview. In it, they show me a page of HTML including a fake widget section that includes this line <div class="widgetServer">http://ctest.discount.test.com</div>.

The question then asks me, what domain server is the widget hosted on. I’m confused as to whether I should clarify if they mean DNS versus a domain server which doesn’t seem to make sense in the context of the question, or if this line with the URL is throwing me off somehow.