diff --git a/app/controllers/api/v1/sites_controller.rb b/app/controllers/api/v1/sites_controller.rb
index 5fc9ac46..2b67864e 100644
--- a/app/controllers/api/v1/sites_controller.rb
+++ b/app/controllers/api/v1/sites_controller.rb
@@ -5,6 +5,7 @@ module Api
     # API para sitios
     class SitesController < BaseController
       SUBDOMAIN = ".#{Site.domain}"
+      TESTING_SUBDOMAIN = ".testing.#{SUBDOMAIN}"
       PARTS = Site.domain.split('.').count
 
       if Rails.env.production?
@@ -14,7 +15,15 @@ module Api
 
       # Lista de nombres de dominios a emitir certificados
       def index
-        render json: sites_names.concat(alternative_names).concat(api_names).concat(www_names)
+        all_names = sites_names.concat(alternative_names).concat(api_names).concat(www_names).uniq.map do |name|
+          canonicalize name
+        end.reject do |name|
+          subdomain? name
+        end.reject do |name|
+          testing? name
+        end.uniq
+
+        render json: all_names
       end
 
       private
@@ -37,24 +46,28 @@ module Api
         name.end_with?(SUBDOMAIN) && name.split('.').count == (PARTS + 1)
       end
 
-      # Nombres de los sitios
-      def sites_names
-        Site.all.order(:name).pluck(:name).map do |name|
-          canonicalize name
-        end.reject do |name|
-          subdomain? name
-        end
+      # Es un dominio de prueba
+      #
+      # @param name [String]
+      # @return [Bool]
+      def testing?(name)
+        name.end_with?(TESTING_SUBDOMAIN) && name.split('.').count == (PARTS + 2)
       end
 
-      # Dominios alternativos
+      # Nombres de los sitios
+      #
+      # @param name [String]
+      # @return [Array<String>]
+      def sites_names
+        Site.all.order(:name).pluck(:name)
+      end
+
+      # Dominios alternativos, incluyendo todas las clases derivadas de
+      # esta.
       #
       # @return [Array<String>]
       def alternative_names
-        hostname_of(DeployAlternativeDomain.all).concat(hostname_of(DeployLocalizedDomain)).map do |name|
-          canonicalize name
-        end.reject do |name|
-          subdomain? name
-        end
+        hostname_of(DeployAlternativeDomain.all)
       end
 
       # Obtener todos los sitios con API habilitada, es decir formulario
@@ -66,10 +79,6 @@ module Api
             .or(Site.where(colaboracion_anonima: true))
             .pluck(:name).map do |name|
               "api.#{name}"
-            end.map do |name|
-              canonicalize name
-            end.reject do |name|
-              subdomain? name
             end
       end