I just noticed this URL as I checked my yahoo account (secondary, yay gmail). I've never seen a URL like this with a string before the www. Is this an illusion (the www is a subdomain that just happens to be named www)? Or is it something that I'm not aware of?

Sorry, I wasn't sure if this is programming question or what, namely because I don't know what it is - that's the point.

I just tried www.m.www.yahoo.com and it does not work, leading me to think it is not a trick subdomain, so the question remains.

and if it is a "mobile friendly designator", how would I use it on a website of mine?

So, (correct me if I'm still getting something wrong here) but www.example.com is really always just a subdomain of example.com, but automatically set up on most servers, so people (like me) don't realize that it isn't anything special. To use the "mobile friendly designator", just set up m. as a normal subdomain. This also explains why search engines treat www.example.com as a different website from example.com (which always just assumed was an oddity with no explanation.



Your guess is right, the www is just a subdomain that happens to be called www. There is nothing special about the www name (unlike http:// for example, which indicates the protocol used).

  • then why does www.m.www.yahoo.com not work? – Nona Urbiz Sep 7 '09 at 19:10
  • Because m.www.yahoo.com might not be set up as a subdomain... – Rowland Shaw Sep 7 '09 at 19:12
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    Putting www in front of a name (any name) actually means something, and won't work if the site operator hasn't set it up that way. Most site operators set up both example.com and www.example.com to work because that's what people expect these days, but they don't have to. – Greg Hewgill Sep 7 '09 at 19:12
  • When I say "nothing special" I mean the name www (which is still a name) carries no additional meaning other than being a part of a web site name. – Greg Hewgill Sep 7 '09 at 19:14
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    Because Yahoo haven't created that subdomain. As Greg says, there is nothing special at all about 'www', it is just another hostname. Just because 'example.com' exists you have no guarantee that 'www.example.com' exists, any more than you do that 'potatopants.example.com' exists. – bobince Sep 7 '09 at 19:14

www.yahoo.com is a subdomain, just like abc.yahoo.com would be, it just points to where yahoo.com does as well. So you can have m.www.yahoo.com as well as w.abc.yahoo.com.

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    in theory, www.yahoo.com could point to somewhere else than yahoo.com – Ikke Sep 7 '09 at 19:32

The "m" prefix usually denotes a mobile-phone-friendly site. "m.www" is unconventional, but perfectly valid.

  • then why does www.m.www.yahoo.com not work? and how would I get this designator to show on a mobile friendly site of mine? – Nona Urbiz Sep 7 '09 at 19:09
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    Because you can't just add "www" on the front of a URL and expect it to work. It's not a magic word, it's just a name. – skaffman Sep 7 '09 at 19:12

This is a DNS decision. There's nothing magical about "www" as a subdomain; it's just a convention. You can have a web site on http://bob.frizzledibble.gopher.wave.pookie.com if you want.

If there is no alias record defined that points www.m.www.yahoo.com somewhere, then it won't be resolvable, and you can't use it. To make a particular name usable, you generally add an A record in your DNS configuration that points to a particular IP address.

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    Wow, I wasn't expecting that domain to actually resolve. Too bad it resolves to an adfarm. – JasonTrue Sep 7 '09 at 19:26
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    Try things like whois microsoft.com or and you'll find some funny things as well. – Arjan Sep 7 '09 at 21:13
  • @Arjan WTF is going on there? – Macha Nov 12 '09 at 18:28

I think you need a better understanding of the domain name system ^^. You have your TLD and your CC (TLD = top level domain, CC = country code). then you have your domain name - so you'd have foo.com or foo.com.uk. Anything on top of that is a subdomain, and needs to be explicitly set. the convention generally is to have www as a subdomain for web pages, but you could easily have pasta.foo.net as well as www.foo.net - and it means about the same at a high level (unless it points at a different server, or an alias- which is another story).

To get a m.foo.com to point at a mobile friendly site, you'd need to register the subdomain and either have it point at your site via a canonical or A domain name record and have it work that way. it isn't magically pointed at that.

  • It would be foo.co.uk actually. As far as I know, only Australia uses .com.au. Most countries use .co.cc. (Or, like Ireland, nothing.) – TRiG Mar 19 '10 at 12:40

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