[ih] Domain Names

[Tony Li]

Other tidbits:

Jack Haverty wrote:
> Programs like Telnet would use the
> local file to change names people typed in, like "MIT-DMS", into the
> appropriate numeric address for opening a network connection.  


Certain operating systems also loaded the hosts file into memory so that 
you could get command completion on host names.


> Of course the changes wouldn't have an effect on any particular
> host until that host had downloaded the latest copy of HOSTS.TXT  That
> could cause lots of confusion since there was little consistency in how
> frequently a particular host got a fresh copy of the hosts.txt file.


Other operating systems had little daemons that would run, download the 
hosts file and install it.  This worked well up until the day when SRI 
put lower case letters in the hosts file and the daemons crashed.  ;-)

See RFC 810 for more details.


> I believe that the "!x!y!z" type of name/route originated from the days
> of dial-up phone networks, in which a computer would periodically dial
> specific other computers and exchange email.  The *user* specified the
> specific route that a message would take.  So a name like X!Y!Z meant
> that machine x would dial up y, exchange the mail, and disconnect.  Then
> Y would dial Z, pass the message, and disconnect.  In those days when
> phone calls were expensive and host administrators had specific ideas
> about where their phone charges could be spent, such flexibility was
> important.  In addition, since not just anyone was allowed to connect to
> the Arpanet/Internet, this made it possible for users on non-network
> hosts to be email-connected to users on Arpanet hosts - you just needed
> to find an x!y!z path that would make the appropriate linkage.  


As mentioned previously, these were part of the UUCP (Unix-to-Unix Copy 
Program) network.  Because nighttime phone calls were cheaper than 
daytime calls, host administrators also circulated information about 
when calls would be made.  This eventually led to the creation of 
routing programs (pathalias) that would take all of the host information 
and execute the Dijkstra Shortest Path First algorithm to figure out how 
to deliver the mail easily.  This also meant that users did not have to 
know the complete route.  For even obscure hosts, it was sufficient to 
simply know the route from one of the very popular hosts (e.g., ucbvax).

Regards,
Tony