Is an invalid valid domain name valid?

Question

Is there a valid domain name used by the convention for test cases when the host should be unavailable? For instance. http://www.unreachable.net/ or http://www.downforever.net/ , which seem to be right now - but for how long?

Or at least an IP address that may not be available? (The special-use IPv4 address specification http://tools.ietf.org/html/rfc3330 does not seem to mention such an address).

UPDATE: the top-level domain is invalid in http://tools.ietf.org/html/rfc2606 is close (thanks to JOTN), but I am looking for a domain that can be resolved for an IP address that is inaccessible (i.e. the server is not responding) .

Cheers, Tamberg

Answer 1

What do you mean by valid? There is a reserved top-level domain: example, invalid, localhost and test.

He talks about those here:

http://en.wikipedia.org/wiki/Top-level_domain#Reserved_domains

Answer 2

http: // localhost: 31337 maybe?