diff --git a/interface-definitions/dns-dynamic.xml b/interface-definitions/dns-dynamic.xml
index e6b9bc318..725ebadac 100644
--- a/interface-definitions/dns-dynamic.xml
+++ b/interface-definitions/dns-dynamic.xml
@@ -1,230 +1,237 @@
 <?xml version="1.0"?>
 <!-- Dynamic DNS configuration -->
 <interfaceDefinition>
   <node name="service">
     <children>
       <node name="dns">
         <properties>
           <help>Domain Name System related services</help>
         </properties>
         <children>
           <node name="dynamic" owner="${vyos_conf_scripts_dir}/dynamic_dns.py">
             <properties>
               <help>Dynamic DNS</help>
               <priority>919</priority>
             </properties>
             <children>
               <tagNode name="interface">
                 <properties>
                   <help>Interface to send DDNS updates for [REQUIRED]</help>
                   <completionHelp>
                     <script>${vyos_completion_dir}/list_interfaces.py</script>
                   </completionHelp>
                 </properties>
                 <children>
                   <tagNode name="rfc2136">
                     <properties>
                       <help>RFC2136 Update name</help>
                     </properties>
                     <children>
                       <leafNode name="key">
                         <properties>
                           <help>File containing the secret key shared with remote DNS server [REQUIRED]</help>
                           <valueHelp>
                             <format>file</format>
                             <description>File in /config/auth directory</description>
                           </valueHelp>
                         </properties>
                       </leafNode>
                       <leafNode name="record">
                         <properties>
                           <help>Record to be updated [REQUIRED]</help>
                           <multi/>
                         </properties>
                       </leafNode>
                       <leafNode name="server">
                         <properties>
                           <help>Server to be updated [REQUIRED]</help>
                         </properties>
                       </leafNode>
                       <leafNode name="ttl">
                         <properties>
                           <help>Time To Live (default: 600)</help>
                           <valueHelp>
                             <format>1-86400</format>
                             <description>DNS forwarding cache size</description>
                           </valueHelp>
                           <constraint>
                             <validator name="numeric" argument="--range 1-86400"/>
                           </constraint>
                         </properties>
                       </leafNode>
                       <leafNode name="zone">
                         <properties>
                           <help>Zone to be updated [REQUIRED]</help>
                         </properties>
                       </leafNode>
                     </children>
                   </tagNode>
                   <tagNode name="service">
                     <properties>
                       <help>Service being used for Dynamic DNS [REQUIRED]</help>
                       <completionHelp>
                         <list>custom afraid changeip cloudflare dnspark dslreports dyndns easydns namecheap noip sitelutions zoneedit</list>
                       </completionHelp>
                       <valueHelp>
                         <format>custom</format>
                         <description>Custom or predefined service</description>
                       </valueHelp>
                       <valueHelp>
                         <format>afraid</format>
                         <description>afraid.org Services</description>
                       </valueHelp>
                       <valueHelp>
                         <format>changeip</format>
                         <description>changeip.com Services</description>
                       </valueHelp>
                       <valueHelp>
                         <format>cloudflare</format>
                         <description>cloudflare.com Services</description>
                       </valueHelp>
                       <valueHelp>
                         <format>dnspark</format>
                         <description>dnspark.com Services</description>
                       </valueHelp>
                       <valueHelp>
                         <format>dslreports</format>
                         <description>dslreports.com Services</description>
                       </valueHelp>
                       <valueHelp>
                         <format>dyndns</format>
                         <description>dyndns.com Services</description>
                       </valueHelp>
                       <valueHelp>
                         <format>easydns</format>
                         <description>easydns.com Services</description>
                       </valueHelp>
                       <valueHelp>
                         <format>namecheap</format>
                         <description>namecheap.com Services</description>
                       </valueHelp>
                       <valueHelp>
                         <format>noip</format>
                         <description>noip.com Services</description>
                       </valueHelp>
                       <valueHelp>
                         <format>sitelutions</format>
                         <description>sitelutions.com Services</description>
                       </valueHelp>
                       <valueHelp>
                         <format>zoneedit</format>
                         <description>zoneedit.com Services</description>
                       </valueHelp>
+                      <constraint>
+                        <regex>(custom|afraid|changeip|cloudflare|dnspark|dslreports|dyndns|easydns|namecheap|noip|sitelutions|zoneedit)</regex>
+                      </constraint>
+                      <constraintErrorMessage>Please choose from the list of allowed services</constraintErrorMessage>
                     </properties>
                     <children>
                       <leafNode name="host-name">
                         <properties>
                           <help>Hostname registered with DDNS service [REQUIRED]</help>
                           <multi/>
                         </properties>
                       </leafNode>
                       <leafNode name="login">
                         <properties>
                           <help>Login for DDNS service [REQUIRED]</help>
                         </properties>
                       </leafNode>
                       <leafNode name="password">
                         <properties>
                           <help>Password for DDNS service [REQUIRED]</help>
                         </properties>
                       </leafNode>
                       <leafNode name="protocol">
                         <properties>
                           <help>ddclient protocol used for DDNS service [REQUIRED FOR CUSTOM]</help>
-                          <valueHelp>
-                            <format>protocol</format>
-                            <description>ddclient protocol</description>
-                          </valueHelp>
+                          <completionHelp>
+                              <list>changeip cloudflare dnspark dslreports1 dyndns2 easydns namecheap noip sitelutions zoneedit1</list>
+                          </completionHelp>
                           <valueHelp>
                             <format>changeip</format>
                             <description>changeip protocol</description>
                           </valueHelp>
                           <valueHelp>
                             <format>cloudflare</format>
                             <description>cloudflare protocol</description>
                           </valueHelp>
                           <valueHelp>
                             <format>dnspark</format>
                             <description>dnspark protocol</description>
                           </valueHelp>
                           <valueHelp>
                             <format>dslreports1</format>
                             <description>dslreports1 protocol</description>
                           </valueHelp>
                           <valueHelp>
                             <format>dyndns2</format>
                             <description>dyndns2 protocol</description>
                           </valueHelp>
                           <valueHelp>
                             <format>easydns</format>
                             <description>easydns protocol</description>
                           </valueHelp>
                           <valueHelp>
                             <format>namecheap</format>
                             <description>namecheap protocol</description>
                           </valueHelp>
                           <valueHelp>
                             <format>noip</format>
                             <description>noip protocol</description>
                           </valueHelp>
                           <valueHelp>
                             <format>sitelutions</format>
                             <description>sitelutions protocol</description>
                           </valueHelp>
                           <valueHelp>
                             <format>zoneedit1</format>
                             <description>zoneedit1 protocol</description>
                           </valueHelp>
+                          <constraint>
+                            <regex>(changeip|cloudflare|dnspark|dslreports1|dyndns2|easydns|namecheap|noip|sitelutions|zoneedit1)</regex>
+                          </constraint>
+                          <constraintErrorMessage>Please choose from the list of allowed protocols</constraintErrorMessage>
                         </properties>
                       </leafNode>
                       <leafNode name="server">
                         <properties>
                           <help>Server to send DDNS update to [REQUIRED FOR CUSTOM]</help>
                           <valueHelp>
                             <format>IPv4</format>
                             <description>IP address of DDNS server</description>
                           </valueHelp>
                           <valueHelp>
                             <format>FQDN</format>
                             <description>Hostname of DDNS server</description>
                           </valueHelp>
                         </properties>
                       </leafNode>
                     </children>
                   </tagNode>
                   <node name="use-web">
                     <properties>
                       <help>Web check used for obtaining the external IP address</help>
                     </properties>
                     <children>
                       <leafNode name="skip">
                         <properties>
                           <help>Skip everything before this on the given URL</help>
                         </properties>
                       </leafNode>
                       <leafNode name="url">
                         <properties>
                           <help>URL to obtain the current external IP address</help>
                         </properties>
                       </leafNode>
                     </children>
                   </node>
                 </children>
               </tagNode>
             </children>
           </node>
         </children>
       </node>
     </children>
   </node>
 </interfaceDefinition>