There are at least two possibilities:
a) Routing the requests on different ports to different machines
b) SRV records (then you don’t need an A record at all). Like MX records which let you use another machine for mail, but not restricted to SMTP. SIP, XMPP and some other services already use it, it is also specified for HTTP and FTP (see ). Too bad it’s not widely implemented yet.

http://ftp.example.com
sorry to spam

An interesting example of the www/no-www phenomenon was for a time http://getfirefox.com - I tried to download Firefox and it gave me an http error page of some kind.

a www is easier to remember and it’s very easy to write a regular expression to highlight www-ified links. These in themselves could be considered good, strong arguments for keeping the www subdomain.

Yes, yes, it’s a host. But syntactically “google” is a second-level domain, so “www” becomes a third level domain - beneath the identifying domain hence “sub” - so it’s a subdomain like it or not, regardless or whatever else it’s called.

Anyway my personal story…… I had a couple of subdomains outside of my control at one point and for security reasons determined that my cookies should not work across subdomains. For this reason, I simply could not have both www and no-www friendliness.

I 301 now to the proper site, for what it’s worth, if someone “gets it wrong” I chose to go with no-www, because I find it easier to type. Either way, some peopel will get it “right” and some will get it “wrong”.

Personally I type in only “google.com” every time. I’ve looked at more web pages than hot dinners, if I had typed in the www every time I’d visited google or altavista I’d probably have stabbed someone by now.
But that’s just me. Definitely, it’s easier to communicate urls with the www - whether over the phone or in an email, it’s much easier to parse. We’re used to hearing it. You know as soon as you hear it that there’s a url coming, even if you don’t know what a url is called.

To those people who claim that having ftp and web on the same domain will hurt expansion, that’s just silly.
- load balancing comes into it at some point
- 301 redirects
- moving services as demand grows, and just mirroring them at the original site

To me, the protocol bit is the important part. http: … It’s insanely hard to remember as a computer newbie - I remember back in the day I had to go get a cereal box or a commercial softdrink giant’s product every time I wanted to type a url.

I was a Windows user - all the directory separators are backwards in Windows. Nutscape and Virus Explorer back then couldn’t handle websites like this, and neither could IIS of the day IIRC:
http://www.somewebsite.com\somedirectory\somefile.someextension

I thought it was silly actually that website urls had all the slashes “around the wrong way” … the http:// helped me learn to get it right.

At the end of the day, it doesn’t matter. Even if your income depends on it, it’s not that big of a deal, you should just do what suits you best. Don’t consider some stupid moral principle. Consider practicalities.
Consider your domain’s cookie policy.

I don’t even advocate naming subdomains after your well known services. yuck. www is implied. website, internet, whatever, if you’re smart enough to figure out that the internet is more than pretty pages, you’re probably smart enough to figure out the rest.
http://ftp.whatever ?? that’s the one I’m most concerned about. Far more important than http://www. - let’s make ftp more accessible, as it’s easier to navigate without pictures, scripts, css, flash and other … bandwidth-eaters.
mail.something ?? pop3?? smtp?? send?? mta?? mx?? trying to predict what someone will type in to reach a given service is simply too hard to bear. Are you gonna set up your mail servers as aliases for all those subdomains??

There’s nothing to stop you, but it won’t normally be necessary. You can’t win them all. When you think you’ve got all your somain-naming bases covered, something else will come up and ruin your well-made plans.

Copy and paste the following into your email program, send it to yourself, and see which produces the clickable link. Anyone in the know knows how pattern matching works. Not only email programs are affected by pattern matching of this type.

*****
http://www.yes-www.com
no-www.org
*****