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

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.