diff --git a/backend/public/js/domains.js b/backend/public/js/domains.js
index 8126037..d8580b6 100644
--- a/backend/public/js/domains.js
+++ b/backend/public/js/domains.js
@@ -2,42 +2,77 @@
    DNS CACHE (mit TTL)
 ========================= */
 
+// =========================
+// DNS CACHE (minimal + robust)
+// =========================
+
+const DNS_CACHE_TTL = 300000      // 5 min für erfolgreiche Antworten
+const DNS_ERROR_TTL = 5000        // 5 sek für Fehler
+
 const dnsCache = {}
+const pending = {}
+
+function normalizeDomain(domain) {
+    return domain.trim().toLowerCase()
+}
 
 async function getDNS(domain){
 
+    if(!domain) return []
+
+    const key = normalizeDomain(domain)
     const now = Date.now()
-    const TTL = 30000 // 30 Sekunden
 
-    if(dnsCache[domain] && (now - dnsCache[domain].time < TTL)){
-        return dnsCache[domain].ips
+    const cached = dnsCache[key]
+
+    // ✅ gültiger Cache
+    if(cached && (now - cached.time < cached.ttl)){
+        return cached.ips
     }
 
-    try{
-
-        const res = await api(API + "/dns/" + domain, {}, { showError: false })
-        const ips = res.ips || []
-
-        dnsCache[domain] = {
-            ips: ips,
-            time: now
-        }
-
-        return ips
-
-    }catch(e){
-
-        dnsCache[domain] = {
-            ips: [],
-            time: now
-        }
-
-        return []
-
+    // ✅ laufende Anfrage wiederverwenden (dedupe)
+    if(pending[key]){
+        return pending[key]
     }
 
+    pending[key] = (async () => {
+        try{
+            const res = await api(
+                API + "/dns/" + encodeURIComponent(key),
+                {},
+                { showError: false }
+            )
+
+            const ips = res?.ips || []
+
+            dnsCache[key] = {
+                ips,
+                time: Date.now(),
+                ttl: DNS_CACHE_TTL
+            }
+
+            return ips
+
+        }catch(e){
+
+            // ❗ Fehler nur kurz cachen
+            dnsCache[key] = {
+                ips: [],
+                time: Date.now(),
+                ttl: DNS_ERROR_TTL
+            }
+
+            return []
+
+        }finally{
+            delete pending[key]
+        }
+    })()
+
+    return pending[key]
 }
 
+
 function dnsStatusMarkup(expectedIp, ips){
 
     if(!ips.length){