diff --git a/src/lib/cc/simple_parser.cc b/src/lib/cc/simple_parser.cc
index de2d308189..bb3c822f24 100644
--- a/src/lib/cc/simple_parser.cc
+++ b/src/lib/cc/simple_parser.cc
@@ -224,6 +224,26 @@ size_t SimpleParser::setDefaults(ElementPtr scope,
             x.reset(new DoubleElement(dbl_value, pos));
             break;
         }
+        case Element::map: {
+            auto data = Element::fromJSON(def_value.value_);
+            if (data->getType() != Element::map) {
+                isc_throw(BadValue,
+                          "Internal error. Incorrect map value type for "
+                          << def_value.name_ << " : " << def_value.value_);
+            }
+            x = data;
+            break;
+        }
+        case Element::list: {
+            auto data = Element::fromJSON(def_value.value_);
+            if (data->getType() != Element::list) {
+                isc_throw(BadValue,
+                          "Internal error. Incorrect list value type for "
+                          << def_value.name_ << " : " << def_value.value_);
+            }
+            x = data;
+            break;
+        }
         default:
             // No default values for null, list or map
             isc_throw(DhcpConfigError,
diff --git a/src/lib/dhcpsrv/parsers/simple_parser4.cc b/src/lib/dhcpsrv/parsers/simple_parser4.cc
index 72a5a8cf70..36188d973f 100644
--- a/src/lib/dhcpsrv/parsers/simple_parser4.cc
+++ b/src/lib/dhcpsrv/parsers/simple_parser4.cc
@@ -70,7 +70,6 @@ const SimpleKeywords SimpleParser4::GLOBAL4_PARAMETERS = {
     { "reservations",                   Element::list },
     { "config-control",                 Element::map },
     { "server-tag",                     Element::string },
-    { "reservation-mode",               Element::string },
     { "reservation-modes",              Element::map },
     { "calculate-tee-times",            Element::boolean },
     { "t1-percent",                     Element::real },
@@ -111,7 +110,6 @@ const SimpleDefaults SimpleParser4::GLOBAL4_DEFAULTS = {
     { "server-hostname",                Element::string,  "" },
     { "boot-file-name",                 Element::string,  "" },
     { "server-tag",                     Element::string,  "" },
-    { "reservation-mode",               Element::string,  "all" },
     { "reservation-modes",              Element::map,     "{\"in-subnet\": true, \"out-of-pool\": true}" },
     { "calculate-tee-times",            Element::boolean, "false" },
     { "t1-percent",                     Element::real,    ".50" },
@@ -208,7 +206,6 @@ const SimpleKeywords SimpleParser4::SUBNET4_PARAMETERS = {
     { "client-class",                   Element::string },
     { "require-client-classes",         Element::list },
     { "reservations",                   Element::list },
-    { "reservation-mode",               Element::string },
     { "reservation-modes",              Element::map, },
     { "relay",                          Element::map },
     { "match-client-id",                Element::boolean },
@@ -326,7 +323,6 @@ const SimpleKeywords SimpleParser4::SHARED_NETWORK4_PARAMETERS = {
     { "server-hostname",                Element::string },
     { "boot-file-name",                 Element::string },
     { "relay",                          Element::map },
-    { "reservation-mode",               Element::string },
     { "reservation-modes",              Element::map },
     { "client-class",                   Element::string },
     { "require-client-classes",         Element::list },
diff --git a/src/lib/dhcpsrv/parsers/simple_parser6.cc b/src/lib/dhcpsrv/parsers/simple_parser6.cc
index 190b8a58a7..7a46012742 100644
--- a/src/lib/dhcpsrv/parsers/simple_parser6.cc
+++ b/src/lib/dhcpsrv/parsers/simple_parser6.cc
@@ -71,7 +71,6 @@ const SimpleKeywords SimpleParser6::GLOBAL6_PARAMETERS = {
     { "reservations",                   Element::list },
     { "config-control",                 Element::map },
     { "server-tag",                     Element::string },
-    { "reservation-mode",               Element::string },
     { "reservation-modes",              Element::map },
     { "calculate-tee-times",            Element::boolean },
     { "t1-percent",                     Element::real },
@@ -107,7 +106,6 @@ const SimpleDefaults SimpleParser6::GLOBAL6_DEFAULTS = {
     { "decline-probation-period",       Element::integer, "86400" }, // 24h
     { "dhcp4o6-port",                   Element::integer, "0" },
     { "server-tag",                     Element::string,  "" },
-    { "reservation-mode",               Element::string,  "all" },
     { "reservation-modes",              Element::map,     "{\"in-subnet\": true, \"out-of-pool\": true}" },
     { "calculate-tee-times",            Element::boolean, "true" },
     { "t1-percent",                     Element::real,    ".50" },
@@ -210,7 +208,6 @@ const SimpleKeywords SimpleParser6::SUBNET6_PARAMETERS = {
     { "client-class",                   Element::string },
     { "require-client-classes",         Element::list },
     { "reservations",                   Element::list },
-    { "reservation-mode",               Element::string },
     { "reservation-modes",              Element::map },
     { "relay",                          Element::map },
     { "user-context",                   Element::map },
@@ -335,7 +332,6 @@ const SimpleKeywords SimpleParser6::SHARED_NETWORK6_PARAMETERS = {
     { "rebind-timer",                   Element::integer },
     { "option-data",                    Element::list },
     { "relay",                          Element::map },
-    { "reservation-mode",               Element::string },
     { "reservation-modes",              Element::map },
     { "client-class",                   Element::string },
     { "require-client-classes",         Element::list },