diff --git a/src/Controller/NameserverController.php b/src/Controller/NameserverController.php
index 90da13b..4805c7e 100644
--- a/src/Controller/NameserverController.php
+++ b/src/Controller/NameserverController.php
@@ -1,7 +1,8 @@
-<?php
-
+<?php declare(strict_types=1);
 namespace App\Controller;
 
+error_reporting(error_level: E_ALL);
+
 use PDO;
 use PDOException;
 
@@ -20,12 +21,13 @@ class NameserverController
 	 */
 	public function findAll(): bool|array
 	{
-		$statement = "
+		$sql = "
             SELECT id, name, a, aaaa, apikey
             FROM " . DatabaseConnection::TABLE_NAMESERVERS;
 		
 		try {
-			$statement = $this->databaseConnection->getConnection()->query($statement);
+			$statement = $this->databaseConnection->getConnection()->prepare(query: $sql);
+			$statement->execute();
 			return $statement->fetchAll(mode: PDO::FETCH_ASSOC);
 		} catch (PDOException $e) {
 			exit($e->getMessage());
@@ -46,10 +48,10 @@ class NameserverController
             WHERE name = :name";
 		
 		try {
-			$statement = $this->databaseConnection->getConnection()->prepare($sql);
+			$statement = $this->databaseConnection->getConnection()->prepare(query: $sql);
 			$statement->bindParam(param: ':name', var: $name);
 			$statement->execute();
-			return $statement->fetch(PDO::FETCH_ASSOC);
+			return $statement->fetch(mode: PDO::FETCH_ASSOC);
 		} catch (PDOException $e) {
 			exit($e->getMessage());
 		}
@@ -69,10 +71,10 @@ class NameserverController
             WHERE id = :id";
 		
 		try {
-			$statement = $this->databaseConnection->getConnection()->prepare($sql);
+			$statement = $this->databaseConnection->getConnection()->prepare(query: $sql);
 			$statement->bindParam(param:':id', var: $id);
 			$statement->execute();
-			return $statement->fetch(PDO::FETCH_ASSOC);
+			return $statement->fetch(mode: PDO::FETCH_ASSOC);
 		} catch (PDOException $e) {
 			exit($e->getMessage());
 		}
@@ -85,16 +87,16 @@ class NameserverController
 	 * @param String $aaaa
 	 * @param String $apikey
 	 *
-	 * @return int
+	 * @return string|false
 	 */
-	public function insert(String $name, String $a, String $aaaa, String $apikey): int
+	public function insert(String $name, String $a, String $aaaa, String $apikey): bool|string
 	{
 		$sql = "
             INSERT INTO " . DatabaseConnection::TABLE_NAMESERVERS . " (name, a, aaaa, apikey)
             VALUES (:name, :a, :aaaa, :apikey)";
 		
 		try {
-			$statement = $this->databaseConnection->getConnection()->prepare($sql);
+			$statement = $this->databaseConnection->getConnection()->prepare(query: $sql);
 			$statement->bindParam(param: ':name', var: $name);
 			$statement->bindParam(param: ':a', var: $a);
 			$statement->bindParam(param: ':aaaa', var: $aaaa);
@@ -119,7 +121,7 @@ class NameserverController
 	 */
 	public function update(Int $id, String $name, String $a, String $aaaa, String $apikey): bool|int
 	{
-		$current = $this->findByID($id);
+		$current = $this->findByID(id: $id);
 		
 		if (empty($name)) {
 			$name = $current['name'] ?? '';
@@ -143,7 +145,7 @@ class NameserverController
             WHERE id = :id";
 		
 		try {
-			$statement = $this->databaseConnection->getConnection()->prepare($sql);
+			$statement = $this->databaseConnection->getConnection()->prepare(query: $sql);
 			$statement->bindParam(param: 'id', var: $id);
 			$statement->bindParam(param: 'name', var: $name);
 			$statement->bindParam(param: 'a', var: $a);
@@ -165,12 +167,12 @@ class NameserverController
 	 */
 	public function delete($id): int
 	{
-		$statement = "
+		$sql = "
             DELETE FROM " . DatabaseConnection::TABLE_NAMESERVERS . "
             WHERE id = :id";
 		
 		try {
-			$statement = $this->databaseConnection->getConnection()->prepare($statement);
+			$statement = $this->databaseConnection->getConnection()->prepare(query: $sql);
 			$statement->bindParam(param: 'id', var: $id);
 			$statement->execute();
 			return $statement->rowCount();
@@ -186,11 +188,11 @@ class NameserverController
 	 */
 	public function getLongestEntry(String $field): int
 	{
-		$statement = "
+		$sql = "
             SELECT MAX(LENGTH(" . $field . ")) as length FROM " . DatabaseConnection::TABLE_NAMESERVERS;
 		
 		try {
-			$statement = $this->databaseConnection->getConnection()->prepare($statement);
+			$statement = $this->databaseConnection->getConnection()->prepare(query: $sql);
 			$statement->execute();
 			$result =  $statement->fetch();
 			return $result['length'];