From f326110514a6ba06852bd4333ebb4166b626d29a Mon Sep 17 00:00:00 2001
From: Shreyas Zare <shreyas@technitium.com>
Date: Sun, 28 Jun 2020 19:32:44 +0530
Subject: [PATCH] CacheZone: optimized code in ContainsNameServerRecords().

---
 DnsServerCore/Dns/Zones/CacheZone.cs | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/DnsServerCore/Dns/Zones/CacheZone.cs b/DnsServerCore/Dns/Zones/CacheZone.cs
index d9d5f978..45fbe3e5 100644
--- a/DnsServerCore/Dns/Zones/CacheZone.cs
+++ b/DnsServerCore/Dns/Zones/CacheZone.cs
@@ -167,8 +167,21 @@ namespace DnsServerCore.Dns.Zones
 
         public override bool ContainsNameServerRecords()
         {
-            IReadOnlyList<DnsResourceRecord> records = QueryRecords(DnsResourceRecordType.NS, false);
-            return (records.Count > 0) && (records[0].Type == DnsResourceRecordType.NS);
+            if (!_entries.TryGetValue(DnsResourceRecordType.NS, out IReadOnlyList<DnsResourceRecord> records))
+                return false;
+
+            foreach (DnsResourceRecord record in records)
+            {
+                if (record.IsStale)
+                    continue;
+
+                if (record.TtlValue < 1u)
+                    continue;
+
+                return true;
+            }
+
+            return false;
         }
 
         #endregion