diff --git a/Apps/AdvancedBlockingApp/App.cs b/Apps/AdvancedBlockingApp/App.cs
index 11c561cf..df37ed34 100644
--- a/Apps/AdvancedBlockingApp/App.cs
+++ b/Apps/AdvancedBlockingApp/App.cs
@@ -998,7 +998,7 @@ namespace AdvancedBlocking
 
             public bool IsZoneAllowed(string domain)
             {
-                domain = domain.ToLower();
+                domain = domain.ToLowerInvariant();
 
                 //allowed, allow list zone, allowedRegex, regex allow list zone, adblock list zone
                 return IsZoneFound(_allowed, domain, out _) || IsZoneFound(_allowListZones, domain, out _, out _) || IsMatchFound(_allowedRegex, domain, out _) || IsMatchFound(_regexAllowListZones, domain, out _, out _) || App.IsZoneAllowed(_adBlockListZones, domain, out _, out _);
@@ -1006,7 +1006,7 @@ namespace AdvancedBlocking
 
             public bool IsZoneBlocked(string domain, out string blockedDomain, out string blockedRegex, out UrlEntry listUrl)
             {
-                domain = domain.ToLower();
+                domain = domain.ToLowerInvariant();
 
                 //blocked
                 if (IsZoneFound(_blocked, domain, out string foundZone1))
@@ -1132,7 +1132,7 @@ namespace AdvancedBlocking
                 _isRegexList = isRegexList;
                 _isAdblockList = isAdblockList;
 
-                _listFilePath = Path.Combine(Path.Combine(_dnsServer.ApplicationFolder, "blocklists"), Convert.ToHexString(SHA256.HashData(Encoding.UTF8.GetBytes(_listUrl.AbsoluteUri))).ToLower());
+                _listFilePath = Path.Combine(Path.Combine(_dnsServer.ApplicationFolder, "blocklists"), Convert.ToHexString(SHA256.HashData(Encoding.UTF8.GetBytes(_listUrl.AbsoluteUri))).ToLowerInvariant());
             }
 
             #endregion
@@ -1387,7 +1387,7 @@ namespace AdvancedBlocking
                                     hostname = secondWord;
                             }
 
-                            hostname = hostname.Trim('.').ToLower();
+                            hostname = hostname.Trim('.').ToLowerInvariant();
 
                             switch (hostname)
                             {
diff --git a/Apps/AdvancedForwardingApp/App.cs b/Apps/AdvancedForwardingApp/App.cs
index c3044587..a26a788c 100644
--- a/Apps/AdvancedForwardingApp/App.cs
+++ b/Apps/AdvancedForwardingApp/App.cs
@@ -81,9 +81,9 @@ namespace AdvancedForwarding
             DnsForwarderRecordData forwarderRecord;
 
             if (configProxyServer is null)
-                forwarderRecord = new DnsForwarderRecordData(protocol, forwarder, dnssecValidation, DnsForwarderRecordProxyType.DefaultProxy, null, 0, null, null);
+                forwarderRecord = new DnsForwarderRecordData(protocol, forwarder, dnssecValidation, DnsForwarderRecordProxyType.DefaultProxy, null, 0, null, null, 0);
             else
-                forwarderRecord = new DnsForwarderRecordData(protocol, forwarder, dnssecValidation, configProxyServer.Type, configProxyServer.ProxyAddress, configProxyServer.ProxyPort, configProxyServer.ProxyUsername, configProxyServer.ProxyPassword);
+                forwarderRecord = new DnsForwarderRecordData(protocol, forwarder, dnssecValidation, configProxyServer.Type, configProxyServer.ProxyAddress, configProxyServer.ProxyPort, configProxyServer.ProxyUsername, configProxyServer.ProxyPassword, 0);
 
             return forwarderRecord;
         }
@@ -306,7 +306,7 @@ namespace AdvancedForwarding
 
             public bool TryGetForwarderRecords(string domain, out IReadOnlyList<DnsForwarderRecordData> forwarderRecords)
             {
-                domain = domain.ToLower();
+                domain = domain.ToLowerInvariant();
 
                 if ((_forwardings is not null) && (_forwardings.Count > 0) && Forwarding.TryGetForwarderRecords(domain, _forwardings, out forwarderRecords))
                     return true;
@@ -367,7 +367,7 @@ namespace AdvancedForwarding
 
                 _domainMap = jsonForwarding.ReadArrayAsMap("domains", delegate (JsonElement jsonDomain)
                 {
-                    return new Tuple<string, object>(jsonDomain.GetString().ToLower(), null);
+                    return new Tuple<string, object>(jsonDomain.GetString().ToLowerInvariant(), null);
                 });
             }
 
@@ -384,7 +384,7 @@ namespace AdvancedForwarding
                 foreach (string domain in domains)
                 {
                     if (DnsClient.IsDomainNameValid(domain))
-                        domainMap.TryAdd(domain.ToLower(), null);
+                        domainMap.TryAdd(domain.ToLowerInvariant(), null);
                 }
 
                 _domainMap = domainMap;
diff --git a/Apps/DnsBlockListApp/App.cs b/Apps/DnsBlockListApp/App.cs
index c16fd682..c0cdc78c 100644
--- a/Apps/DnsBlockListApp/App.cs
+++ b/Apps/DnsBlockListApp/App.cs
@@ -731,7 +731,7 @@ namespace DnsBlockList
                             responseTXT = line;
 
                             if (DnsClient.IsDomainNameValid(domain))
-                                domains.Enqueue(new BlockEntry<string>(domain.ToLower(), responseA, responseTXT));
+                                domains.Enqueue(new BlockEntry<string>(domain.ToLowerInvariant(), responseA, responseTXT));
                         }
 
                         _blockListFileLastModified = File.GetLastWriteTimeUtc(fS.SafeFileHandle);
@@ -793,7 +793,7 @@ namespace DnsBlockList
 
             public override bool IsBlocked(string domain, out string foundDomain, out IPAddress responseA, out string responseTXT)
             {
-                if (IsDomainBlocked(domain.ToLower(), out BlockEntry<string> domainEntry))
+                if (IsDomainBlocked(domain.ToLowerInvariant(), out BlockEntry<string> domainEntry))
                 {
                     foundDomain = domainEntry.Key;
                     responseA = domainEntry.ResponseA is null ? _responseA : domainEntry.ResponseA;
diff --git a/Apps/FailoverApp/HealthService.cs b/Apps/FailoverApp/HealthService.cs
index 40c741b3..f4fe43e7 100644
--- a/Apps/FailoverApp/HealthService.cs
+++ b/Apps/FailoverApp/HealthService.cs
@@ -391,7 +391,7 @@ namespace Failover
 
         public HealthCheckResponse QueryStatus(string domain, DnsResourceRecordType type, string healthCheck, Uri healthCheckUrl, bool tryAdd)
         {
-            domain = domain.ToLower();
+            domain = domain.ToLowerInvariant();
 
             string healthMonitorKey = GetHealthMonitorKey(domain, type, healthCheck, healthCheckUrl);
 
diff --git a/Apps/FilterAaaaApp/App.cs b/Apps/FilterAaaaApp/App.cs
index cc8a5a47..37f3110d 100644
--- a/Apps/FilterAaaaApp/App.cs
+++ b/Apps/FilterAaaaApp/App.cs
@@ -30,7 +30,7 @@ using TechnitiumLibrary.Net.Dns.ResourceRecords;
 
 namespace FilterAaaa
 {
-    public class App : IDnsApplication, IDnsPostProcessor
+    public sealed class App : IDnsApplication, IDnsPostProcessor
     {
         #region variables