We are all familiar with websites that start with www (World Wide Web). I have seen some sites that start with www3 or www5. I have also seen websites with no www of any kind.
What’s the difference? Are there others?
Technically, the URL begins with a “scheme”, which is probably “http” in the case you’ve given. If it is an http URL, it has a colon (
and two slashes (//), followed by an Internet host.
The difference is that they are different hosts, with different names. In one case, the http server is on a machine named “www.whatever.whocares.xxx” and in the other it is “www3.idontknow.something.xxx”.
Everything you could ever care to know about URLs is here. Especially relevant is RFC 1738 wherein the syntax of URLs is discussed. From section 3.1:
host
The fully qualified domain name of a network host, or its IP
address as a set of four decimal digit groups separated by
".". Fully qualified domain names take the form as described
in Section 3.5 of RFC 1034 [13] and Section 2.1 of RFC 1123
[5]: a sequence of domain labels separated by ".", each domain
label starting and ending with an alphanumerical character and
possibly also containing "-" characters. The rightmost domain
label will never start with a digit, though, which
syntactically distinguishes all domain names from the IP
addresses.
The “www” on a website is purely arbitrary and there is no reason (other than convention) to use it. Domain names have two main elements: the name of the domain (straightdope) and the suffix (currently .com, .edu, .gov, .mil, .org, and .net).
Anything before these elements are assigned by the domain user. It was usually the name of a server on the domain. When the WWW was set up, a lot of domains assigned “www” as the name of the server.
But there is no rule that you need to use that. You can use any valid characters (note at the top of this you see the domain http://boards.straightdope.com). You can name the individual computer something that duplicates the name of another domain, and as long as it’s on your domain, it’ll work fine.
Some domains don’t bother with the first part; others will automatically redirect you to the right computer (try going to amazon.com, for instance).
I’d assume www2 is used to direct to the second webserver, either because they need two or because the first one was obsolete.
As well as one for each country, such as .us and .uk.
At the time, of course, the web was not such a dominant protocol, and it was useful to distinguish the web server from the ftp or telnet or pop3 or smtp or gopher or any of a variety of other servers. Much easier to use standard names, rather than remembering that your web server is named “Bill” while your telnet server is named “Monica”. (Actually, monica is the name of a remote telnet server that I used frequently in college)
There are also some new top-level domains; .info and .biz are the most common of these, but according to IANA, there are also. .coop, .aero, .museum, and .name. And there’s the ‘infrastructure’ domain, .arpa, which I will not try to explain at this hour.
Google can be reached at
w.google.com
If you’re at a public computer, this will save you a precious two strokes. Big deal. However, if the browser remembers previous address entries and autocompletes your typing, you just have to type “w.” from then on, since no other URLs were likely entered in this way.
E.g., my daughter’s web page’s server’s domain starts with “fff”.
you should be able to resolve any domain name without the “www” in front of it if it “normally” has one. AFAIK it is similar to not having to type the “index.html” or “index.htm” or “default.htm” or whatever in (which is why you should always be able to access a sight with a trailing slash).
http://straightdope.com/
http://google.com/
http://thespark.com/
I almost never put the “www” in.
Sometimes leaving out the www. doesn’t work. It’s up to the network administrator to set up the server so that
bogusname.com is pointed to the same server as www.bogusname.com.
They might point to two different web servers. That happens sometimes.
I hate when a commercial on TV leaves out the www., but then you go to that address and it doesn’t work. The IBM ads in Canada tell you to go to ibm.ca, but there’s no server at that address. It’s bad enough that they didn’t account for it to begin with, but to actually tell people to go to that address is another thing.
Usually…but occasionally I find one that doesn’t. It’s not related to the default page on the server, but to the DNS record, which is what translates domain names (like www.google.com) to an IP address. Most admins set the record for the root domain (google.com) to the same IP as the web server (www.google.com) to make sure that people get to the site with less trouble. Same for w.google.com and ww.google.com–they are there to get you to the site even if you type it incorrectly. Not really a feature of any software, but an admins trick.
When you see urls with a www1 through wwwn prefix, it usually means that a clustered server is handling the load for that website. At high volume sites, multiple, identical servers will be linked together by a load balancer. Each server has a copy of the website or server code. When a request for a particular page or function comes in, the load balancer routes the request to one of the machines based on a pre-defined set of rules. For example, you connect to www.popularsite.com. The load balancer knows that machines 1-4 are busy, so it hands the request off to #5, and the url that pops up in your browser is www5.popularsite.com. eBay is a good place to observe this frmo an end user perspective.
At a properly configured site, www.popularsite.com or popularsite.com will bring you to the same page. Anything before the domain name in the url represents the internal structure of the site and usually doesn’t matter to the end user. Hosting sites are the most notable exception: YourHost.SomeHostCompany.com.
I turned off Auto-parse URLs - DrMatrix
Aww crap. I should never post this late. I didn’t realize the sample url I provided pointed to a real site. Don’t click on it. It’s an example. Thanks!
.com refers to the giant DNS server somewhere that has a directory of all the computers under it which possess .com names, like straightdope.com and yahoo.com.
The same thing holds true with them. When your computer wants www.straightdope.com, it asks the computer (returned by .com as straightdope.com) what the IP address of www is. It returns you the address of the server that’s a ‘child’ of straightdope.com which possess the www name.
When I do my comp sci homework I log into solaris.remote.cs.rpi.edu which tells my computer to look for the solaris server off the remote server off the cs server off the rpi server off the edu server.
The www is a convention for referring to the machine that is responsible for web page hosting on a particular domain. If you wanted to FTP in, you’d most likely communicate with ftp.something.com because that’s most likely (by convention) the machine that’s set up for FTP usage.
This doesn’t mean that all web sites have to start with www, it just means that if you have a domain like straigtdope.com, most people expect that your HTML server will reside at www.straightdope.com by default.
I always found it funny that, with everyone snapping up easy to remember domains like fish.com or help.net, every address starts with www. ‘W’ is the longest of all the letters to pronounce.
So on TV or radio ads your neat little “Fish dot com” blows out to “Double U Double U Double U dot fish dot com”
IMHO “they” should make it shorter to say, like aaa or something we can turn into a word.
But I don’t think whoever started using “WWW” umpteen years ago was thinking about the speed it takes to say www.coke.com in a $3 million 30 second SuperBowl commercial.
Thanks for the correction on the sub-domain resolution.
Samboy: the other point of note is that saying ‘www’ takes longer than saying ‘world wide web’.
Some abbreviation!