When should one use a 'www' subdomain?

Question

When browsing through the internet for the last few years, I\'m seeing more and more pages getting rid of the \'www\' subdomain.

Are there any good reasons to use or

Answer 1

There is no huge advantage to including-it or not-including-it and no one objectively-best strategy. “no-www.org” is a silly load of old dogma trying to present itself as definitive fact.

If the “big organisation that has many different services and doesn't want to have to dedicate the bare domain name to being a web server” scenario doesn't apply to you (and in reality it rarely does), which address you choose is a largely cultural matter. Are people where you are used to seeing a bare “example.org” domain written on advertising materials, would they immediately recognise it as a web address without the extra ‘www’ or ‘http://’? In Japan, for example, you would get funny looks for choosing the non-www version.

Whichever you choose, though, be consistent. Make both www and non-www versions accessible, but make one of them definitive, always link to that version, and make the other redirect to it (permanently, status code 301). Having both hostnames respond directly is bad for SEO, and serving any old hostname that resolves to your server leaves you open to DNS rebinding attacks.

Answer 2

Apart from the load optimization regarding cookies, there is also a DNS related reason for using the www subdomain. You can't use CNAME to the naked domain. On yes-www.org yes-www.org it says:

When using a provider such as Heroku or Akamai to host your web site, the provider wants to be able to update DNS records in case it needs to redirect traffic from a failing server to a healthy server. This is set up using DNS CNAME records, and the naked domain cannot have a CNAME record. This is only an issue if your site gets large enough to require highly redundant hosting with such a service.