piet@NIC.EU.net (Piet Beertema) (12/19/90)
All mail/systems managers please take note that CS is now an official top level domain. I've already seen several mails pass by on mcsun.EU.net, which is where the MX records for .cs point to. All those mails are doomed to fail, since they weren't really meant for a host in Czecho-Slovakia, but for an internal host and resulted from the use of abbreviated addressing of the form user@host.cs within a domain like cs.foo.bar. Note that according to RFC822 par. 6.2.2, abbreviated addressing is bound to restrictions. Hosts that allow abbreviated addresses that end on a domain name that is - or may sooner or later be - a top level domain violate these restrictions. Officially only 2-letter codes that are listed in ISO-3166 can become top level domains, but given political reality ISO-3166 won't last forever and it's safer to *never* use a 2-letter code for a subdomain. -- Piet Beertema, EUnet-NIC, Amsterdam (hostmaster@NIC.EU.net)