diff --git a/src/dns_conf.c b/src/dns_conf.c
index 2137d11489..cb2a52e87d 100644
--- a/src/dns_conf.c
+++ b/src/dns_conf.c
@@ -1221,6 +1221,10 @@ static struct dns_conf_group *_config_rule_group_get(const char *group_name)
 
 struct dns_conf_group *dns_server_get_rule_group(const char *group_name)
 {
+	if (dns_conf_rule.group_num <= 1) {
+		return dns_conf_rule.default_conf;
+	}
+
 	struct dns_conf_group *rule_group = _config_rule_group_get(group_name);
 	if (rule_group) {
 		return rule_group;
@@ -1239,6 +1243,10 @@ static struct dns_conf_group *_config_rule_group_new(const char *group_name)
 	struct dns_conf_group *rule_group = NULL;
 	uint32_t key = 0;
 
+	if (group_name == NULL) {
+		return NULL;
+	}
+
 	rule_group = malloc(sizeof(*rule_group));
 	if (rule_group == NULL) {
 		return NULL;
@@ -1255,6 +1263,7 @@ static struct dns_conf_group *_config_rule_group_new(const char *group_name)
 
 	key = hash_string(group_name);
 	hash_add(dns_conf_rule.group, &rule_group->node, key);
+	dns_conf_rule.group_num++;
 
 	return rule_group;
 }
@@ -1267,6 +1276,7 @@ static void _config_rule_group_remove(struct dns_conf_group *rule_group)
 	Destroy_Radix(rule_group->address_rule.ipv4, _config_ip_iter_free, NULL);
 	Destroy_Radix(rule_group->address_rule.ipv6, _config_ip_iter_free, NULL);
 	free(rule_group->soa_table);
+	dns_conf_rule.group_num--;
 
 	free(rule_group);
 }
diff --git a/src/dns_conf.h b/src/dns_conf.h
index 61b88ff0d0..e719264e9f 100644
--- a/src/dns_conf.h
+++ b/src/dns_conf.h
@@ -454,6 +454,7 @@ struct dns_conf_group {
 struct dns_conf_rule {
 	struct dns_conf_group *default_conf;
 	DECLARE_HASHTABLE(group, 8);
+	int group_num;
 };
 
 struct dns_client_rule {