diff --git a/app/api/repp/nameservers_v1.rb b/app/api/repp/nameservers_v1.rb
index d653adf7f..71fde5aba 100644
--- a/app/api/repp/nameservers_v1.rb
+++ b/app/api/repp/nameservers_v1.rb
@@ -29,7 +29,7 @@ module Repp
         }
 
         begin
-          current_user.registrar.replace_nameservers(hostname, new_attributes)
+          affected_domains = current_user.registrar.replace_nameservers(hostname, new_attributes)
         rescue ActiveRecord::RecordInvalid => e
           error!({ errors: e.record.errors.full_messages.map { |error| { title: error } } }, 400)
         end
@@ -37,7 +37,8 @@ module Repp
         status 200
         @response = { data: { type: 'nameserver',
                               id: params[:data][:attributes][:hostname],
-                              attributes: params[:data][:attributes] } }
+                              attributes: params[:data][:attributes],
+                              affected_domains: affected_domains } }
       end
     end
   end
diff --git a/app/models/registrar.rb b/app/models/registrar.rb
index 54e007133..de02d42a7 100644
--- a/app/models/registrar.rb
+++ b/app/models/registrar.rb
@@ -145,7 +145,7 @@ class Registrar < ActiveRecord::Base
         original_nameserver.destroy!
       end
 
-      domain_list
+      domain_list.uniq.sort
     end
   end
 
diff --git a/doc/repp/v1/nameservers.md b/doc/repp/v1/nameservers.md
index 702a0c186..c1269f92a 100644
--- a/doc/repp/v1/nameservers.md
+++ b/doc/repp/v1/nameservers.md
@@ -35,6 +35,7 @@ Content-Type: application/json
             "ipv4": ["192.0.2.1", "192.0.2.2"],
             "ipv6": ["2001:db8::1", "2001:db8::2"]
         },
+        "affected_domains": ["example.com", "example.org"]
     }
 }
 ```
diff --git a/test/integration/api/nameservers/put_test.rb b/test/integration/api/nameservers/put_test.rb
index 416510541..e840cfcfc 100644
--- a/test/integration/api/nameservers/put_test.rb
+++ b/test/integration/api/nameservers/put_test.rb
@@ -41,11 +41,12 @@ class APINameserversPutTest < ActionDispatch::IntegrationTest
     assert_equal nameserver_hash, nameservers(:metro_ns1).reload.attributes
   end
 
-  def test_returns_new_nameserver_record
+  def test_returns_new_nameserver_record_and_affected_domain
     request_params = { format: :json, data: { type: 'nameserver', id: 'ns1.bestnames.test',
                                               attributes: { hostname: 'ns55.bestnames.test',
                                                             ipv4: ['192.0.2.55'],
                                                             ipv6: ['2001:db8::55'] } } }
+
     put '/repp/v1/registrar/nameservers', request_params, { 'HTTP_AUTHORIZATION' => http_auth_key }
 
     assert_response 200
@@ -53,7 +54,8 @@ class APINameserversPutTest < ActionDispatch::IntegrationTest
                             id: 'ns55.bestnames.test',
                             attributes: { hostname: 'ns55.bestnames.test',
                                           ipv4: ['192.0.2.55'],
-                                          ipv6: ['2001:db8::55'] } } }),
+                                          ipv6: ['2001:db8::55'] },
+                            affected_domains: ["airport.test", "shop.test"] } }),
                  JSON.parse(response.body, symbolize_names: true)
   end
 
diff --git a/test/integration/registrar/bulk_change/nameserver_test.rb b/test/integration/registrar/bulk_change/nameserver_test.rb
index 20fd6617d..d1dbfc012 100644
--- a/test/integration/registrar/bulk_change/nameserver_test.rb
+++ b/test/integration/registrar/bulk_change/nameserver_test.rb
@@ -16,7 +16,8 @@ class RegistrarAreaNameserverBulkChangeTest < ActionDispatch::IntegrationTest
                                                                      basic_auth: ['test_goodnames', 'testtest'])
                      .to_return(body: { data: [{
                                                  type: 'nameserver',
-                                                 id: 'new-ns.bestnames.test'
+                                                 id: 'new-ns.bestnames.test',
+                                                 affected_domains: ["airport.test", "shop.test"]
                                                }] }.to_json, status: 200)
 
     visit registrar_domains_url
diff --git a/test/models/registrar/replace_nameservers_test.rb b/test/models/registrar/replace_nameservers_test.rb
index c247b2860..5bcbb83d1 100644
--- a/test/models/registrar/replace_nameservers_test.rb
+++ b/test/models/registrar/replace_nameservers_test.rb
@@ -5,7 +5,7 @@ class ReplaceNameserversTest < ActiveSupport::TestCase
     @registrar = registrars(:bestnames)
   end
 
-  def test_replace_nameservers_in_bulk_returns_domain_names
+  def test_replace_nameservers_in_bulk_returns_sorted_domain_names
     new_attributes = { hostname: 'ns-updated1.bestnames.test', ipv4: '192.0.3.1',
                        ipv6: '2001:db8::2' }
     result = @registrar.replace_nameservers('ns1.bestnames.test', new_attributes)