diff --git a/src/Controller/DomainController.php b/src/Controller/DomainController.php
index 77d283c..7945aae 100644
--- a/src/Controller/DomainController.php
+++ b/src/Controller/DomainController.php
@@ -67,6 +67,30 @@ class DomainController
 	}
 	
 	
+	function updateSlaveZones()
+	{
+		if ($this->config['verbose']) {
+			echo 'Delete all slave zones';
+		}
+		
+		$zones = glob(pattern: $this->localZonesDir . '*');
+		foreach ($zones as $zone) {
+			unlink(filename: $zone);
+		}
+		
+		$domains = $this->domainRepository->findAll();
+		
+		foreach ($domains as $domain) {
+			if ($this->config['verbose']) {
+				echo 'Create zone: ' . $domain->getName() . PHP_EOL;
+			}
+			$this->createSlaveZoneFile(domain: $domain);
+		}
+		
+		$this->createIncludeFile();
+	}
+	
+	
 	function deleteOnNameservers(Domain $domain)
 	{
 		if ($this->config['debug']) {
@@ -202,25 +226,28 @@ class DomainController
 	 */
 	public function createSlaveZoneFile(Domain $domain): void
 	{
+		$domainName = $domain->getName();
 		if ($this->config['debug']) {
-			$domainName = $domain->getName();
 			$this->log->debug(message: "createZoneFile($domainName)");
 		}
 		
 		// check if we're a master zone
 		if ($this->isMasterZone(domain: $domain)) {
-			echo 'We are zone master for ' . $domain->getName() . PHP_EOL;
+			echo 'We are zone master for ' . $domainName . PHP_EOL;
 			exit(1);
 		}
 		
-		if ($zonefile = fopen(filename: $this->localZonesDir . $domain->getName(), mode: 'w')) {
+		if ($zonefile = fopen(filename: $this->localZonesDir . $domainName, mode: 'w')) {
 			$panelName = $domain->getPanel();
-			$panel = $this->panelRepository->findByName(name: $panelName);
+			if (!$panel = $this->panelRepository->findByName(name: $panelName)) {
+				echo "Error: Panel $panelName doesn't exist." . PHP_EOL;
+				die();
+			}
 			$a = $panel->getA();
 			$aaaa = $panel->getAaaa();
-			fputs(stream: $zonefile, data: 'zone "' . $domain->getName() . '"' . ' IN {' . PHP_EOL);
+			fputs(stream: $zonefile, data: 'zone "' . $domainName . '"' . ' IN {' . PHP_EOL);
 			fputs(stream: $zonefile, data: "\ttype slave;" . PHP_EOL);
-			fputs(stream: $zonefile, data: "\tfile \"" . $this->zoneCachePath . $domain->getName() . '.db";' . PHP_EOL);
+			fputs(stream: $zonefile, data: "\tfile \"" . $this->zoneCachePath . $domainName . '.db";' . PHP_EOL);
 			fputs(stream: $zonefile, data: "\tmasters {" . PHP_EOL);
 			if (!empty($a)) {
 				fputs(stream: $zonefile, data: "\t\t" . $a . ';' . PHP_EOL);
@@ -231,10 +258,10 @@ class DomainController
 			fputs(stream: $zonefile, data: "\t};" . PHP_EOL);
 			fputs(stream: $zonefile, data: "};" . PHP_EOL);
 		}
-		$this->createIncludeFile();
 	}
 	
-	private function isMasterZone(Domain $domain): bool
+	
+	public function isMasterZone(Domain $domain): bool
 	{
 		if (file_exists(filename: '/etc/bind/keyhelp_domains/' . $domain->getName())) {
 			return true;