diff --git a/src/etc/inc/plugins.inc.d/dhcpd.inc b/src/etc/inc/plugins.inc.d/dhcpd.inc
index da2ce6b1c..a0bea2b65 100644
--- a/src/etc/inc/plugins.inc.d/dhcpd.inc
+++ b/src/etc/inc/plugins.inc.d/dhcpd.inc
@@ -1129,14 +1129,12 @@ EOD;
         }
 
         $dhcpdifs[] = get_real_interface($dhcpif);
-        if (!empty($newzone['domain-name'])) {
-            if (isset($dhcpifconf['ddnsupdate'])) {
-                $newzone['dns-servers'] = array($dhcpifconf['ddnsdomainprimary']);
-                $newzone['ddnsdomainkeyname'] = $dhcpifconf['ddnsdomainkeyname'];
-                $newzone['ddnsdomainkey'] = $dhcpifconf['ddnsdomainkey'];
-                $newzone['ddnsdomainalgorithm'] = !empty($dhcpifconf['ddnsdomainalgorithm']) ? $dhcpifconf['ddnsdomainalgorithm'] : "hmac-md5";
-                $ddns_zones[] = $newzone;
-            }
+        if (!empty($newzone['domain-name']) && isset($dhcpifconf['ddnsupdate']) && is_ipaddrv4($dhcpifconf['ddnsdomainprimary'])) {
+            $newzone['dns-servers'] = array($dhcpifconf['ddnsdomainprimary']);
+            $newzone['ddnsdomainkeyname'] = $dhcpifconf['ddnsdomainkeyname'];
+            $newzone['ddnsdomainkey'] = $dhcpifconf['ddnsdomainkey'];
+            $newzone['ddnsdomainalgorithm'] = !empty($dhcpifconf['ddnsdomainalgorithm']) ? $dhcpifconf['ddnsdomainalgorithm'] : "hmac-md5";
+            $ddns_zones[] = $newzone;
         }
 
         if ($dhcpifconf['omapi'] && !$omapi_added) {
@@ -1173,40 +1171,21 @@ EOD;
     }
 }
 
-function dhcpd_zones($ddns_zones)
+function dhcpd_zones($ddns_zones, $ipproto = 'inet')
 {
     $dhcpdconf = '';
-
     if (is_array($ddns_zones)) {
         $added_zones = array();
         $added_keys = array();
         foreach ($ddns_zones as $zone) {
-            if (!is_array($zone) || empty($zone) || !is_array($zone['dns-servers'])) {
-                continue;
-            }
-
-            $primary = $zone['dns-servers'][0];
-            $secondary = empty($zone['dns-servers'][1]) ? "" : $zone['dns-servers'][1];
-
-            // Make sure we aren't using any invalid or IPv6 DNS servers.
-            if (!is_ipaddrv4($primary)) {
-                if (is_ipaddrv4($secondary)) {
-                    $primary = $secondary;
-                    $secondary = "";
-                } else {
-                    continue;
-                }
-            }
-
+            $versionsuffix = $ipproto == "inet6" ? "6" : "";
             // We don't need to add zones multiple times.
             foreach (array($zone['domain-name'], $zone['ptr-domain']) as $domain) {
                 if (!empty($domain) && !in_array($domain, $added_zones)) {
                     /* dhcpdconf2 is injected *after* the key */
                     $dhcpdconf2 = "zone {$domain}. {\n";
-                    $dhcpdconf2 .= "  primary {$primary};\n";
-                    if (is_ipaddrv4($secondary)) {
-                        $dhcpdconf2 .= "  secondary {$secondary};\n";
-                    }
+                    // XXX: $zone['dns-servers'] only contains one item, ref $newzone['dns-servers']
+                    $dhcpdconf2 .= "  primary{$versionsuffix} {$zone['dns-servers'][0]};\n";
                     if (!empty($zone['ddnsdomainkeyname']) && !empty($zone['ddnsdomainkey'])) {
                         if (!in_array($zone['ddnsdomainkeyname'], $added_keys)) {
                             $dhcpdconf .= "key {$zone['ddnsdomainkeyname']} {\n";
@@ -1406,7 +1385,7 @@ EOD;
 
     $dhcpdv6ifs = array();
     $ddns_zones = array();
-    $nsupdate = false;
+    $need_ddns_updates = false;
 
     foreach ($dhcpdv6cfg as $dhcpv6if => $dhcpv6ifconf) {
         if (!isset($dhcpv6ifconf['enable']) || !isset($iflist[$dhcpv6if])) {
@@ -1434,6 +1413,7 @@ EOD;
         $newzone = array();
 
         if (isset($dhcpv6ifconf['ddnsupdate'])) {
+            $need_ddns_updates = true;
             if (!empty($dhcpv6ifconf['ddnsdomain'])) {
                 $dnscfgv6 .= "  ddns-domainname \"{$dhcpv6ifconf['ddnsdomain']}\";\n";
                 $newzone['domain-name'] = $dhcpv6ifconf['ddnsdomain'];
@@ -1441,7 +1421,20 @@ EOD;
                 $newzone['domain-name'] = $config['system']['domain'];
             }
 
-            $nsupdate = true;
+            $subnetv6 = explode("/", $networkv6)[0];
+            $addr = inet_pton($subnetv6);
+            $addr_unpack = unpack('H*hex', $addr);
+            $addr_hex = $addr_unpack['hex'];
+            $revsubnet = array_reverse(str_split($addr_hex));
+            foreach ($revsubnet as $octet) {
+                if ($octet == "0") {
+                    array_shift($revsubnet);
+                } else {
+                    break;
+                }
+            }
+
+            $newzone['ptr-domain'] = implode(".", $revsubnet) . ".ip6.arpa";
         }
 
         if (isset($dhcpv6ifconf['dnsserver'][0])) {
@@ -1544,15 +1537,12 @@ EOD;
             }
         }
 
-        if (!empty($newzone['domain-name'])) {
-            if (isset($dhcpv6ifconf['ddnsupdate'])) {
-                $newzone['dns-servers'] = array($dhcpv6ifconf['ddnsdomainprimary']);
-                $newzone['ddnsdomainkeyname'] = $dhcpv6ifconf['ddnsdomainkeyname'];
-                $newzone['ddnsdomainkey'] = $dhcpv6ifconf['ddnsdomainkey'];
-                /* XXX not implemented for IPv6 */
-                $newzone['ddnsdomainalgorithm'] = 'hmac-md5';
-                $ddns_zones[] = $newzone;
-            }
+        if (!empty($newzone['domain-name']) && isset($dhcpv6ifconf['ddnsupdate']) && is_ipaddrv6($dhcpv6ifconf['ddnsdomainprimary'])) {
+            $newzone['dns-servers'] = array($dhcpv6ifconf['ddnsdomainprimary']);
+            $newzone['ddnsdomainkeyname'] = $dhcpv6ifconf['ddnsdomainkeyname'];
+            $newzone['ddnsdomainkey'] = $dhcpv6ifconf['ddnsdomainkey'];
+            $newzone['ddnsdomainalgorithm'] = !empty($dhcpv6ifconf['ddnsdomainalgorithm']) ? $dhcpv6ifconf['ddnsdomainalgorithm'] : "hmac-md5";
+            $ddns_zones[] = $newzone;
         }
 
         if (preg_match("/poes/si", $dhcpv6if)) {
@@ -1571,9 +1561,10 @@ EOD;
         }
     }
 
-    if ($nsupdate) {
+    if ($need_ddns_updates) {
         $dhcpdv6conf .= "\nddns-update-style interim;\n";
-        $dhcpdv6conf .= dhcpd_zones($ddns_zones);
+        $dhcpdv6conf .= "update-static-leases on;\n";
+        $dhcpdv6conf .= dhcpd_zones($ddns_zones, "inet6");
     } else {
         $dhcpdv6conf .= "\nddns-update-style none;\n";
     }
diff --git a/src/www/services_dhcpv6.php b/src/www/services_dhcpv6.php
index c000116ef..b637c5b91 100644
--- a/src/www/services_dhcpv6.php
+++ b/src/www/services_dhcpv6.php
@@ -64,7 +64,7 @@ if ($_SERVER['REQUEST_METHOD'] === 'GET') {
         $pconfig['prefixrange_length'] = $config['dhcpdv6'][$if]['prefixrange']['prefixlength'];
     }
     $config_copy_fieldsnames = array('defaultleasetime', 'maxleasetime', 'domainsearchlist', 'ddnsdomain',
-        'ddnsdomainprimary', 'ddnsdomainkeyname', 'ddnsdomainkey', 'bootfile_url', 'netmask',
+        'ddnsdomainprimary', 'ddnsdomainkeyname', 'ddnsdomainkey', 'ddnsdomainalgorithm', 'bootfile_url', 'netmask',
         'numberoptions', 'dhcpv6leaseinlocaltime', 'staticmap');
     foreach ($config_copy_fieldsnames as $fieldname) {
         if (isset($config['dhcpdv6'][$if][$fieldname])) {
@@ -235,7 +235,7 @@ if ($_SERVER['REQUEST_METHOD'] === 'GET') {
 
             // simple 1-on-1 copy
             $config_copy_fieldsnames = array('defaultleasetime', 'maxleasetime', 'netmask', 'domainsearchlist',
-              'ddnsdomain', 'ddnsdomainprimary', 'ddnsdomainkeyname', 'ddnsdomainkey', 'bootfile_url',
+              'ddnsdomain', 'ddnsdomainprimary', 'ddnsdomainkeyname', 'ddnsdomainkey', 'ddnsdomainalgorithm', 'bootfile_url',
               'dhcpv6leaseinlocaltime');
             foreach ($config_copy_fieldsnames as $fieldname) {
                 if (!empty($pconfig[$fieldname])) {
@@ -612,6 +612,16 @@ if (isset($config['interfaces'][$if]['dhcpd6track6allowoverride'])) {
                           <input name="ddnsdomainkeyname" type="text" id="ddnsdomainkeyname" size="20" value="<?=$pconfig['ddnsdomainkeyname'];?>" />
                           <?=gettext("Enter the dynamic DNS domain key secret which will be used to register client names in the DNS server.");?>
                           <input name="ddnsdomainkey" type="text" id="ddnsdomainkey" size="20" value="<?=$pconfig['ddnsdomainkey'];?>" />
+                          <?=gettext("Choose the dynamic DNS domain key algorithm.");?><br />
+                          <select name='ddnsdomainalgorithm' id="ddnsdomainalgorithm" class="selectpicker">
+<?php
+                          foreach (array("hmac-md5", "hmac-sha512") as $algorithm) :?>
+                              <option value="<?=$algorithm;?>" <?=$pconfig['ddnsdomainalgorithm'] == $algorithm ? "selected=\"selected\"" :"";?>>
+                                <?=$algorithm;?>
+                              </option>
+<?php
+                          endforeach; ?>
+                          </select>
                         </div>
                       </td>
                     </tr>