diff --git a/backend/src/applications/applications.service.ts b/backend/src/applications/applications.service.ts
index 2887b16..5e7e213 100644
--- a/backend/src/applications/applications.service.ts
+++ b/backend/src/applications/applications.service.ts
@@ -30,6 +30,33 @@ export class ApplicationsService {
     private configService: ConfigService,
   ) {}
 
+  private toDnsLabel(value: string): string {
+    return (value || '')
+      .toLowerCase()
+      .replace(/[^a-z0-9-]/g, '-')
+      .replace(/-+/g, '-')
+      .replace(/^-|-$/g, '')
+      .slice(0, 63);
+  }
+
+  private async generateRandomSubdomain(baseLabel: string): Promise<string> {
+    const base = this.toDnsLabel(baseLabel) || 'app';
+    const suffixLenBytes = 5; // 10 hex chars
+    const suffixLen = suffixLenBytes * 2;
+
+    for (let attempt = 0; attempt < 10; attempt++) {
+      const suffix = crypto.randomBytes(suffixLenBytes).toString('hex'); // [0-9a-f]
+      const maxBaseLen = 63 - 1 - suffixLen; // base + '-' + suffix
+      const truncatedBase = base.slice(0, Math.max(1, maxBaseLen)).replace(/-+$/g, '');
+      const candidate = `${truncatedBase}-${suffix}`;
+
+      const exists = await this.appsRepository.findOne({ where: { subdomain: candidate } });
+      if (!exists) return candidate;
+    }
+
+    throw new BadRequestException('Failed to generate a unique subdomain. Please try again.');
+  }
+
   async create(userId: string, dto: CreateApplicationDto, userRole?: string): Promise<Application> {
     dto = normalizeCreateApplicationDto(dto);
     const productType = dto.productType ?? ProductType.APPLICATION;
@@ -83,7 +110,10 @@ export class ApplicationsService {
       ? 80
       : 3000;
 
-    const subdomain = `${dto.name}-${userId.split('-')[0]}`;
+    const baseLabel = dto.name;
+    const subdomain = customDomain
+      ? `${this.toDnsLabel(baseLabel)}-${this.toDnsLabel(userId.split('-')[0])}`
+      : await this.generateRandomSubdomain(baseLabel);
     const platformDomain = this.configService.get('platform.domain') || 'apps.cloudhost.ir';
 
     const app = this.appsRepository.create({
diff --git a/frontend/src/app/dashboard/deploy/page.tsx b/frontend/src/app/dashboard/deploy/page.tsx
index 9d4bc8c..412cc1a 100644
--- a/frontend/src/app/dashboard/deploy/page.tsx
+++ b/frontend/src/app/dashboard/deploy/page.tsx
@@ -2086,7 +2086,7 @@ export default function DeployPage() {
                                   Type: <strong>CNAME</strong>
                                 </p>
                                 <p className="text-xs font-mono bg-gray-50 rounded px-2 py-1">
-                                  Value: <strong>{form.name}-{(user?.id || '').split('-')[0]}.apps.cloudhost.ir</strong>
+                                  Value: <strong>your app Platform Domain (after creation)</strong>
                                 </p>
                               </div>
                               <p>4. If using a root domain (without www), use a registrar that supports CNAME flattening (e.g. Cloudflare).</p>
@@ -2096,20 +2096,8 @@ export default function DeployPage() {
                             {/* CNAME target copy box */}
                             <div className="mt-3 bg-blue-50 rounded-lg p-3 border border-blue-100">
                               <p className="text-xs text-blue-700 font-medium mb-1">CNAME Target:</p>
-                              <div className="flex items-center gap-2">
-                                <code className="text-sm font-mono text-blue-900 bg-blue-100 px-2 py-1 rounded flex-1 truncate">
-                                  {form.name}-{(user?.id || '').split('-')[0]}.apps.cloudhost.ir
-                                </code>
-                                <button
-                                  type="button"
-                                  onClick={() => {
-                                    navigator.clipboard.writeText(`${form.name}-${(user?.id || '').split('-')[0]}.apps.cloudhost.ir`);
-                                    toast.success('Copied!');
-                                  }}
-                                  className="text-blue-600 hover:text-blue-800 p-1 shrink-0"
-                                >
-                                  <Copy className="w-4 h-4" />
-                                </button>
+                              <div className="text-sm text-blue-900 bg-blue-100 px-2 py-1 rounded">
+                                After the app is created, open its page and copy the “Platform Domain” value shown in the Domains/Settings section.
                               </div>
                             </div>
                           </div>
@@ -3055,7 +3043,7 @@ export default function DeployPage() {
               <div className="mt-4 bg-gray-50 rounded-lg p-3 border border-gray-200">
                 <p className="text-xs font-medium text-gray-600 mb-1">Required CNAME record:</p>
                 <code className="text-xs font-mono text-gray-800">
-                  {customDomainInput} → {form.name}-{(user?.id || '').split('-')[0]}.apps.cloudhost.ir
+                  {customDomainInput} → your app Platform Domain (after creation)
                 </code>
               </div>
             </div>