diff --git a/Apps/GeoDistanceApp/Address.cs b/Apps/GeoDistanceApp/Address.cs
index 4bdaf738..dff59f4f 100644
--- a/Apps/GeoDistanceApp/Address.cs
+++ b/Apps/GeoDistanceApp/Address.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
@@ -105,18 +105,22 @@ namespace GeoDistance
                 case DnsResourceRecordType.AAAA:
                     Location location = null;
 
-                    bool ecsUsed = false;
+                    byte scopePrefixLength = 0;
                     EDnsClientSubnetOptionData requestECS = request.GetEDnsClientSubnetOption();
                     if (requestECS is not null)
                     {
-                        if (_maxMind.DatabaseReader.TryCity(requestECS.Address, out CityResponse csResponse) && csResponse.Location.HasCoordinates)
-                        {
-                            ecsUsed = true;
+                        if ((_maxMind.IspReader is not null) && _maxMind.IspReader.TryIsp(requestECS.Address, out IspResponse csIsp) && (csIsp.Network is not null))
+                            scopePrefixLength = (byte)csIsp.Network.PrefixLength;
+                        else if ((_maxMind.AsnReader is not null) && _maxMind.AsnReader.TryAsn(requestECS.Address, out AsnResponse csAsn) && (csAsn.Network is not null))
+                            scopePrefixLength = (byte)csAsn.Network.PrefixLength;
+                        else
+                            scopePrefixLength = requestECS.SourcePrefixLength;
+
+                        if (_maxMind.CityReader.TryCity(requestECS.Address, out CityResponse csResponse) && csResponse.Location.HasCoordinates)
                             location = csResponse.Location;
-                        }
                     }
 
-                    if ((location is null) && _maxMind.DatabaseReader.TryCity(remoteEP.Address, out CityResponse response) && response.Location.HasCoordinates)
+                    if ((location is null) && _maxMind.CityReader.TryCity(remoteEP.Address, out CityResponse response) && response.Location.HasCoordinates)
                         location = response.Location;
 
                     using (JsonDocument jsonDocument = JsonDocument.Parse(appRecordData))
@@ -182,19 +186,10 @@ namespace GeoDistance
                         if (answers.Count > 1)
                             answers.Shuffle();
 
-                        EDnsOption[] options;
+                        EDnsOption[] options = null;
 
-                        if (requestECS is null)
-                        {
-                            options = null;
-                        }
-                        else
-                        {
-                            if (ecsUsed)
-                                options = EDnsClientSubnetOptionData.GetEDnsClientSubnetOption(requestECS.SourcePrefixLength, requestECS.SourcePrefixLength, requestECS.Address);
-                            else
-                                options = EDnsClientSubnetOptionData.GetEDnsClientSubnetOption(requestECS.SourcePrefixLength, 0, requestECS.Address);
-                        }
+                        if (requestECS is not null)
+                            options = EDnsClientSubnetOptionData.GetEDnsClientSubnetOption(requestECS.SourcePrefixLength, scopePrefixLength, requestECS.Address);
 
                         return Task.FromResult(new DnsDatagram(request.Identifier, true, request.OPCODE, true, false, request.RecursionDesired, isRecursionAllowed, false, false, DnsResponseCode.NoError, request.Question, answers, null, null, _dnsServer.UdpPayloadSize, EDnsHeaderFlags.None, options));
                     }