[BCP126]   Best Current Practice 126,
              <https://www.rfc-editor.org/info/bcp126>.
              At the time of writing, this BCP comprises the following:

              Abley, J. and K. Lindqvist, "Operation of Anycast
              Services", BCP 126, RFC 4786, DOI 10.17487/RFC4786,
              December 2006, <https://www.rfc-editor.org/info/rfc4786>.