diff --git a/Apps/SplitHorizonApp/AddressTranslation.cs b/Apps/SplitHorizonApp/AddressTranslation.cs
index f10c576f..d59e5501 100644
--- a/Apps/SplitHorizonApp/AddressTranslation.cs
+++ b/Apps/SplitHorizonApp/AddressTranslation.cs
@@ -1,6 +1,6 @@
 /*
 Technitium DNS Server
-Copyright (C) 2023  Shreyas Zare (shreyas@technitium.com)
+Copyright (C) 2024  Shreyas Zare (shreyas@technitium.com)
 
 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
@@ -32,13 +32,13 @@ using TechnitiumLibrary.Net.Dns.ResourceRecords;
 
 namespace SplitHorizon
 {
-    public class AddressTranslation : IDnsApplication, IDnsPostProcessor, IDnsAuthoritativeRequestHandler
+    public sealed class AddressTranslation : IDnsApplication, IDnsPostProcessor, IDnsAuthoritativeRequestHandler
     {
         #region variables
 
         bool _enableAddressTranslation;
-        IReadOnlyDictionary<NetworkAddress, string> _networkGroupMap;
-        IReadOnlyDictionary<string, Group> _groups;
+        Dictionary<NetworkAddress, string> _networkGroupMap;
+        Dictionary<string, Group> _groups;
 
         #endregion
 
@@ -312,9 +312,9 @@ namespace SplitHorizon
             readonly string _name;
             readonly bool _enabled;
             readonly bool _translateReverseLookups;
-            readonly IReadOnlyDictionary<IPAddress, IPAddress> _externalToInternalTranslation;
-            readonly IReadOnlyDictionary<IPAddress, IPAddress> _internalToExternalTranslation;
-            readonly IReadOnlyList<KeyValuePair<NetworkAddress, NetworkAddress>> _externalToInternalNetworkTranslation;
+            readonly Dictionary<IPAddress, IPAddress> _externalToInternalTranslation;
+            readonly Dictionary<IPAddress, IPAddress> _internalToExternalTranslation;
+            readonly List<KeyValuePair<NetworkAddress, NetworkAddress>> _externalToInternalNetworkTranslation;
 
             #endregion
 
diff --git a/Apps/SplitHorizonApp/SimpleAddress.cs b/Apps/SplitHorizonApp/SimpleAddress.cs
index af6dc579..ee297737 100644
--- a/Apps/SplitHorizonApp/SimpleAddress.cs
+++ b/Apps/SplitHorizonApp/SimpleAddress.cs
@@ -1,6 +1,6 @@
 /*
 Technitium DNS Server
-Copyright (C) 2023  Shreyas Zare (shreyas@technitium.com)
+Copyright (C) 2024  Shreyas Zare (shreyas@technitium.com)
 
 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
@@ -32,11 +32,11 @@ using TechnitiumLibrary.Net.Dns.ResourceRecords;
 
 namespace SplitHorizon
 {
-    public class SimpleAddress : IDnsApplication, IDnsAppRecordRequestHandler
+    public sealed class SimpleAddress : IDnsApplication, IDnsAppRecordRequestHandler
     {
         #region variables
 
-        static IReadOnlyDictionary<string, List<NetworkAddress>> _networks;
+        static Dictionary<string, List<NetworkAddress>> _networks;
 
         #endregion
 
@@ -239,7 +239,7 @@ namespace SplitHorizon
 
         #region properties
 
-        internal static IReadOnlyDictionary<string, List<NetworkAddress>> Networks
+        internal static Dictionary<string, List<NetworkAddress>> Networks
         { get { return _networks; } }
 
         public string Description
diff --git a/Apps/SplitHorizonApp/SimpleCNAME.cs b/Apps/SplitHorizonApp/SimpleCNAME.cs
index b7771d3d..db6186bc 100644
--- a/Apps/SplitHorizonApp/SimpleCNAME.cs
+++ b/Apps/SplitHorizonApp/SimpleCNAME.cs
@@ -1,6 +1,6 @@
 /*
 Technitium DNS Server
-Copyright (C) 2023  Shreyas Zare (shreyas@technitium.com)
+Copyright (C) 2024  Shreyas Zare (shreyas@technitium.com)
 
 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
@@ -29,7 +29,7 @@ using TechnitiumLibrary.Net.Dns.ResourceRecords;
 
 namespace SplitHorizon
 {
-    public class SimpleCNAME : IDnsApplication, IDnsAppRecordRequestHandler
+    public sealed class SimpleCNAME : IDnsApplication, IDnsAppRecordRequestHandler
     {
         #region IDisposable