Returns the domain part of a host, such as rubyonrails.org in "www.rubyonrails.org". You can specify a different tld_length, such as 2 to catch rubyonrails.co.uk in "www.rubyonrails.co.uk".

Source Code

# File action_controller/request.rb, line 204
def domain(tld_length = 1)
  return nil unless named_host?(host)

  host.split('.').last(1 + tld_length).join('.')
end