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From "Leif W" <>
Subject Re: [users@httpd] What defines www2? - WAAAY OT?
Date Sat, 22 Jan 2005 16:40:59 GMT
> Rich Bowen; 2005 January 17 Monday 13:43
> JM Fraser wrote:
> | Perhaps a daft question, but I have Googled and not found an answer. 
> Some
> | websites start with WWW(?), why is this and where can one instigate 
> this
> | change and does Apache accept this FQDN as it would any other?
> Server names are completely arbitrary. You can call your server www,
> www2, waldo, or happy_fun_dragon. It's entirely up to you. The
> convention of naming servers after the service that runs on them makes
> sense, but is by no means required.

Actually I thought you can't use underscores with DNS?  Has to be 
dashes, last time I checked (which was a while ago).

Anyways the question may be taken literally as WWW means World Wide Web, 
that's why.  Most of us know that and started thinking historically, 
philosophically and whimsically.  ;-)

As others pointed out, the sub-domain names were conventionally used on 
a per-server basis.  This was possibly more necessary in the past when 
multiple servers (either daemon programs or virtual hosts) simply 
wouldn't run on a single machine, probably way before the www, so each 
was on it's own machine.  It's a common convention for organizational 
administration.  It makes it easier to distinguish between services when 
looking at log files.  In the current time, a single domain on a single 
server could easily be overloaded, so there's often a different daemon 
(FTP, mail, www) on differnt boxes.  Each box or just each virtual host 
might have a different function, so different names are used.

Most of the time, is mapped to, so a person 
can use either.  When other services are offered to the internet (mail, 
FTP, SSH, and so on) it just makes sense to separate the names, even if 
it's on the same box.  Maybe at some later time you want to move 
services to separate boxes due to resource utilization.  Now they MUST 
have a separate name.  So using sub-domains lends itself to scalability.

Also, it later became a convention to let client programs look at the 
host name and take a guess at which port to contact. 
would be 21, would be 80, and so on.  Without those 
subdomains, a client can either try nothing, try one thing, or try 
multiple things in what amounts to a simple port scan, which is 
extremely inefficient and often considered hostile.  Most of the time 
we're using web browsers, so they try port 80 only.


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