[BCP17]    Best Current Practice 17,
              <https://www.rfc-editor.org/info/bcp17>.
              At the time of writing, this BCP comprises the following:

              Hamilton, M. and R. Wright, "Use of DNS Aliases for
              Network Services", BCP 17, RFC 2219, DOI 10.17487/RFC2219,
              October 1997, <https://www.rfc-editor.org/info/rfc2219>.