您也可以根据子域路由：

class SupportSubdomain
  def self.matches?(request)
    request.subdomain == "support"
  end
end

Basecamp::Application.routes do
  constraints(SupportSubdomain) do
    match "/foo/bar",:to => "foo#bar"
  end
end

如果你使用2.3,你需要使用一个插件,如subdomain-fu.