There is a problem with the experimental scenarios which use the DNS for resolving URNs - e.g. uri.lut.ac.uk .
Domain names are actually quite variable.
They usually incorporate some variant of the organization's name, and often the names of departments and groups within those departments. This brings us back once more to the dangling links problem. X.500 is believed by some to be unsuitable for this sort of large scale usage, because of both the complexity of the underlying OSI architecture, and the lack of a scaleable mechanism for distributing meta-information. Centroids explicitly address the issue of distributing meta-information, though the technology itself is in its infancy. Centroids may be generated automatically from the contents of gopher and World-Wide Web servers, and from anonymous FTP archives via IAFA templates.