It all depends on the domain name and how common (and pronounceable) it is.
".com" is dot com. ".us" is dot you ess.
".ru" to me is dot are you.
But if I used it commonly in a group of people, it might become "dot roo."
As an example, many people are familiar with ".org" as "dot org." But those not familiar with the domain would probably spell it out "dot oh are gee."