I don’t really have experience with the resource root URL setting, but from what I understand, you don’t “generate” it; rather, you register another hostname in DNS, pointing to your Jenkins controller host, and configure that as the resource root in Jenkins. Then when a user tries to access “untrusted” files (such as files in workspaces) with a Web browser, Jenkins redirects to a URL within the resource root and serves the file from there.
So, you should talk about the resource hostname with the people who maintain your DNS. They might decide that you need to use a separate second-level domain (like GitHub has github.com for its own UI but githubusercontent.com for untrusted files). Jenkins does not mandate such a strict separation and would be happy with a subdomain for the resources, but perhaps your corporate network has some other web servers that need to be protected from potentially malicious scripts in untrusted files that Jenkins serves under the resource root URL.