diff --git a/app/Http/Controllers/SystemController.php b/app/Http/Controllers/SystemController.php
index 8baf1bc..903d5eb 100644
--- a/app/Http/Controllers/SystemController.php
+++ b/app/Http/Controllers/SystemController.php
@@ -5,7 +5,7 @@ namespace App\Http\Controllers;
 use Illuminate\Http\Request;
 use Illuminate\Support\Arr;
 
-use App\Models\{Address,System,Zone};
+use App\Models\{Address,System,SystemZone,Zone};
 use App\Rules\{FidoInteger,TwoByteInteger};
 
 class SystemController extends Controller
@@ -234,6 +234,12 @@ class SystemController extends Controller
 
 		$zo = Zone::findOrFail($validate['zone_id']);
 
+		// If this session is for the ZC, it now becomes the default.
+		if (in_array(DomainController::NODE_ZC,$o->match($zo)->pluck('role')->toArray())) {
+			SystemZone::where('default',TRUE)->update(['default'=>FALSE]);
+			$validate['default'] = TRUE;
+		}
+
 		$o->sessions()->attach($zo,$validate);
 
 		return redirect()->to(sprintf('ftn/system/addedit/%d',$o->id));
@@ -319,6 +325,7 @@ class SystemController extends Controller
 	 * @param Request $request
 	 * @param System $so
 	 * @param Address $o
+	 * @return \Illuminate\Contracts\Foundation\Application|\Illuminate\Contracts\View\Factory|\Illuminate\Contracts\View\View|\Illuminate\Http\RedirectResponse
 	 * @throws \Illuminate\Auth\Access\AuthorizationException
 	 */
 	public function mov_address(Request $request,System $so,Address $o)
diff --git a/app/Http/Controllers/ZoneController.php b/app/Http/Controllers/ZoneController.php
index b301412..292bfc6 100644
--- a/app/Http/Controllers/ZoneController.php
+++ b/app/Http/Controllers/ZoneController.php
@@ -99,15 +99,20 @@ class ZoneController extends Controller
 	 * Set address as default for zone
 	 *
 	 * @param Request $request
-	 * @param Address $o
+	 * @param Zone $o
+	 * @throws \Illuminate\Auth\Access\AuthorizationException
 	 */
 	public function api_default(Request $request,Zone $o)
 	{
 		$this->authorize('admin',$o);
 
 		$default = $o->systems->where('pivot.default',TRUE);
+
+		if ($default->first()->addresses->pluck('role')->search(DomainController::NODE_ZC) !== FALSE)
+			abort(412);
+
 		if ($default->count() && ($default->first()->id != $request->sid))
-			abort(404);
+			abort(409);
 
 		$o->systems()->updateExistingPivot($request->sid,[
 			'default' => (bool)$request->set,
diff --git a/app/Models/SystemZone.php b/app/Models/SystemZone.php
index ca4b451..9eb5f63 100644
--- a/app/Models/SystemZone.php
+++ b/app/Models/SystemZone.php
@@ -7,6 +7,7 @@ use Illuminate\Database\Eloquent\Model;
 class SystemZone extends Model
 {
 	protected $table = 'system_zone';
+	public $timestamps = FALSE;
 
 	public function system()
 	{
diff --git a/resources/views/system/addedit.blade.php b/resources/views/system/addedit.blade.php
index 28291b1..aee5065 100644
--- a/resources/views/system/addedit.blade.php
+++ b/resources/views/system/addedit.blade.php
@@ -305,9 +305,11 @@ use App\Http\Controllers\DomainController as DC;
 
 						$(item).find('i').removeClass('spinner-grow spinner-grow-sm');
 					},
-					error: function() {
+					error: function(e) {
 						$(item).find('i').removeClass('spinner-grow spinner-grow-sm');
-						alert('That didnt work? Please try again....');
+
+						if (e.status != 412)
+							alert('That didnt work? Please try again....');
 					},
 					url: '{{ url('api/default') }}/'+item.attributes.itemid.nodeValue,
 					cache: false