ServerFailure for DNS requests about a couple specific sites

[Cyberbeni]

[2026-07-29 10:43:10 Local] DNS Server failed to resolve the request 'www.mbhbank.hu. HTTPS IN' using forwarders: 193.110.56.8, 193.110.57.4.
System.Net.Sockets.SocketException (111): Connection refused
   at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.ThrowException(SocketError error, CancellationToken cancellationToken)
   at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.System.Threading.Tasks.Sources.IValueTaskSource.GetResult(Int16 token)
   at TechnitiumLibrary.Net.Dns.ClientConnection.TcpClientConnection.GetConnectionAsync(CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\ClientConnection\TcpClientConnection.cs:line 182
   at TechnitiumLibrary.Net.Dns.ClientConnection.TcpClientConnection.SendDnsDatagramAsync(DnsDatagram request, Int32 timeout, Transaction transaction, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\ClientConnection\TcpClientConnection.cs:line 262
   at TechnitiumLibrary.Net.Dns.ClientConnection.TcpClientConnection.QueryAsync(DnsDatagram request, Int32 timeout, Int32 retries, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\ClientConnection\TcpClientConnection.cs:line 322
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass89_0.<<InternalResolveAsync>g__DoResolveAsync|1>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4566
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass89_0.<<InternalResolveAsync>g__DoResolveAsync|1>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4792
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass89_0.<<InternalResolveAsync>g__DoResolveAsync|1>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4482
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.InternalResolveAsync(DnsDatagram request, Func`3 getValidatedResponseAsync, Boolean doNotReorderNameServers, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4941
   at TechnitiumLibrary.Net.Dns.DnsClient.InternalResolveAsync(DnsDatagram request, Func`3 getValidatedResponseAsync, Boolean doNotReorderNameServers, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4883
   at TechnitiumLibrary.Net.Dns.DnsClient.GetDnsKeyForAsync(IReadOnlyList`1 lastDSRecords, DnsClient dnsClient, IDnsCache cache, UInt16 udpPayloadSize, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 3314
   at TechnitiumLibrary.Net.Dns.DnsClient.FindDnsKeyForAsync(String ownerName, DnsClass class, IReadOnlyList`1 currentDnsKeyRecords, DnsClient dnsClient, IDnsCache cache, UInt16 udpPayloadSize, DnsDatagram originalResponse, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 3284
   at TechnitiumLibrary.Net.Dns.DnsClient.DnssecValidateResponseAsync(DnsDatagram response, IReadOnlyList`1 lastDSRecords, DnsClient dnsClient, IDnsCache cache, UInt16 udpPayloadSize, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 2780
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass91_0.<<InternalDnssecResolveAsync>b__0>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 5056
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass89_0.<<InternalResolveAsync>g__DoResolveAsync|1>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4623
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass89_0.<<InternalResolveAsync>g__DoResolveAsync|1>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4792
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass89_0.<<InternalResolveAsync>g__DoResolveAsync|1>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4482
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.InternalResolveAsync(DnsDatagram request, Func`3 getValidatedResponseAsync, Boolean doNotReorderNameServers, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4941
   at TechnitiumLibrary.Net.Dns.DnsClient.InternalResolveAsync(DnsDatagram request, Func`3 getValidatedResponseAsync, Boolean doNotReorderNameServers, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4883
   at TechnitiumLibrary.Net.Dns.DnsClient.InternalDnssecResolveAsync(DnsQuestionRecord question, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 5027
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass93_0.<<InternalCachedResolveQueryAsync>b__0>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 5154
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.ResolveQueryAsync(DnsQuestionRecord question, Func`2 resolveAsync) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4285
   at TechnitiumLibrary.Net.Dns.DnsClient.InternalCachedResolveQueryAsync(DnsQuestionRecord question, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 5136
   at DnsServerCore.Dns.DnsServer.DefaultRecursiveResolveAsync(DnsQuestionRecord question, NetworkAddress eDnsClientSubnet, IDnsCache dnsCache, Boolean dnssecValidation, Boolean skipDnsAppAuthoritativeRequestHandlers, CancellationToken cancellationToken) in Z:\Technitium\Projects\DnsServer\DnsServerCore\Dns\DnsServer.cs:line 5256
   at DnsServerCore.Dns.DnsServer.RecursiveResolverBackgroundTaskAsync(DnsQuestionRecord question, NetworkAddress eDnsClientSubnet, Boolean advancedForwardingClientSubnet, IReadOnlyList`1 conditionalForwarders, Boolean dnssecValidation, Boolean cachePrefetchOperation, Boolean cacheRefreshOperation, Boolean skipDnsAppAuthoritativeRequestHandlers, TaskCompletionSource`1 taskCompletionSource) in Z:\Technitium\Projects\DnsServer\DnsServerCore\Dns\DnsServer.cs:line 5039

[2026-07-29 06:43:14 Local] DNS Server failed to resolve the request 'pkm.budapestbank.hu. A IN' using forwarders: 193.110.56.8, 193.110.57.4.
TechnitiumLibrary.Net.Dns.DnsClientNoResponseException: DnsClient failed to resolve the request 'budapestbank.hu. DNSKEY IN': request timed out for name server [193.110.56.8].
   at TechnitiumLibrary.Net.Dns.ClientConnection.TcpClientConnection.QueryAsync(DnsDatagram request, Int32 timeout, Int32 retries, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\ClientConnection\TcpClientConnection.cs:line 368
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass89_0.<<InternalResolveAsync>g__DoResolveAsync|1>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4566
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass89_0.<<InternalResolveAsync>g__DoResolveAsync|1>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4792
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass89_0.<<InternalResolveAsync>g__DoResolveAsync|1>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4482
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.InternalResolveAsync(DnsDatagram request, Func`3 getValidatedResponseAsync, Boolean doNotReorderNameServers, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4941
   at TechnitiumLibrary.Net.Dns.DnsClient.InternalResolveAsync(DnsDatagram request, Func`3 getValidatedResponseAsync, Boolean doNotReorderNameServers, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4883
   at TechnitiumLibrary.Net.Dns.DnsClient.GetDnsKeyForAsync(IReadOnlyList`1 lastDSRecords, DnsClient dnsClient, IDnsCache cache, UInt16 udpPayloadSize, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 3314
   at TechnitiumLibrary.Net.Dns.DnsClient.FindDnsKeyForAsync(String ownerName, DnsClass class, IReadOnlyList`1 currentDnsKeyRecords, DnsClient dnsClient, IDnsCache cache, UInt16 udpPayloadSize, DnsDatagram originalResponse, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 3284
   at TechnitiumLibrary.Net.Dns.DnsClient.DnssecValidateResponseAsync(DnsDatagram response, IReadOnlyList`1 lastDSRecords, DnsClient dnsClient, IDnsCache cache, UInt16 udpPayloadSize, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 2780
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass91_0.<<InternalDnssecResolveAsync>b__0>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 5056
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass89_0.<<InternalResolveAsync>g__DoResolveAsync|1>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4623
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass89_0.<<InternalResolveAsync>g__DoResolveAsync|1>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4792
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass89_0.<<InternalResolveAsync>g__DoResolveAsync|1>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4482
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.InternalResolveAsync(DnsDatagram request, Func`3 getValidatedResponseAsync, Boolean doNotReorderNameServers, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4941
   at TechnitiumLibrary.Net.Dns.DnsClient.InternalResolveAsync(DnsDatagram request, Func`3 getValidatedResponseAsync, Boolean doNotReorderNameServers, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4883
   at TechnitiumLibrary.Net.Dns.DnsClient.InternalDnssecResolveAsync(DnsQuestionRecord question, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 5027
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass93_0.<<InternalCachedResolveQueryAsync>b__0>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 5154
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.ResolveQueryAsync(DnsQuestionRecord question, Func`2 resolveAsync) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4285
   at TechnitiumLibrary.Net.Dns.DnsClient.InternalCachedResolveQueryAsync(DnsQuestionRecord question, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 5136
   at DnsServerCore.Dns.DnsServer.DefaultRecursiveResolveAsync(DnsQuestionRecord question, NetworkAddress eDnsClientSubnet, IDnsCache dnsCache, Boolean dnssecValidation, Boolean skipDnsAppAuthoritativeRequestHandlers, CancellationToken cancellationToken) in Z:\Technitium\Projects\DnsServer\DnsServerCore\Dns\DnsServer.cs:line 5256
   at DnsServerCore.Dns.DnsServer.RecursiveResolverBackgroundTaskAsync(DnsQuestionRecord question, NetworkAddress eDnsClientSubnet, Boolean advancedForwardingClientSubnet, IReadOnlyList`1 conditionalForwarders, Boolean dnssecValidation, Boolean cachePrefetchOperation, Boolean cacheRefreshOperation, Boolean skipDnsAppAuthoritativeRequestHandlers, TaskCompletionSource`1 taskCompletionSource) in Z:\Technitium\Projects\DnsServer\DnsServerCore\Dns\DnsServer.cs:line 5039
[2026-07-29 06:43:14 Local] DNS Server failed to resolve the request 'pkm.budapestbank.hu. HTTPS IN' using forwarders: 193.110.56.8, 193.110.57.4.
System.Net.Sockets.SocketException (111): Connection refused
   at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.System.Threading.Tasks.Sources.IValueTaskSource.GetResult(Int16 token)
   at TechnitiumLibrary.Net.Dns.ClientConnection.TcpClientConnection.GetConnectionAsync(CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\ClientConnection\TcpClientConnection.cs:line 182
   at TechnitiumLibrary.Net.Dns.ClientConnection.TcpClientConnection.SendDnsDatagramAsync(DnsDatagram request, Int32 timeout, Transaction transaction, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\ClientConnection\TcpClientConnection.cs:line 262
   at TechnitiumLibrary.Net.Dns.ClientConnection.TcpClientConnection.QueryAsync(DnsDatagram request, Int32 timeout, Int32 retries, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\ClientConnection\TcpClientConnection.cs:line 322
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass89_0.<<InternalResolveAsync>g__DoResolveAsync|1>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4566
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass89_0.<<InternalResolveAsync>g__DoResolveAsync|1>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4792
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass89_0.<<InternalResolveAsync>g__DoResolveAsync|1>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4482
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.InternalResolveAsync(DnsDatagram request, Func`3 getValidatedResponseAsync, Boolean doNotReorderNameServers, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4941
   at TechnitiumLibrary.Net.Dns.DnsClient.InternalResolveAsync(DnsDatagram request, Func`3 getValidatedResponseAsync, Boolean doNotReorderNameServers, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4883
   at TechnitiumLibrary.Net.Dns.DnsClient.GetDnsKeyForAsync(IReadOnlyList`1 lastDSRecords, DnsClient dnsClient, IDnsCache cache, UInt16 udpPayloadSize, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 3314
   at TechnitiumLibrary.Net.Dns.DnsClient.FindDnsKeyForAsync(String ownerName, DnsClass class, IReadOnlyList`1 currentDnsKeyRecords, DnsClient dnsClient, IDnsCache cache, UInt16 udpPayloadSize, DnsDatagram originalResponse, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 3284
   at TechnitiumLibrary.Net.Dns.DnsClient.DnssecValidateResponseAsync(DnsDatagram response, IReadOnlyList`1 lastDSRecords, DnsClient dnsClient, IDnsCache cache, UInt16 udpPayloadSize, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 2780
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass91_0.<<InternalDnssecResolveAsync>b__0>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 5056
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass89_0.<<InternalResolveAsync>g__DoResolveAsync|1>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4623
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass89_0.<<InternalResolveAsync>g__DoResolveAsync|1>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4792
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass89_0.<<InternalResolveAsync>g__DoResolveAsync|1>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4482
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.InternalResolveAsync(DnsDatagram request, Func`3 getValidatedResponseAsync, Boolean doNotReorderNameServers, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4941
   at TechnitiumLibrary.Net.Dns.DnsClient.InternalResolveAsync(DnsDatagram request, Func`3 getValidatedResponseAsync, Boolean doNotReorderNameServers, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4883
   at TechnitiumLibrary.Net.Dns.DnsClient.InternalDnssecResolveAsync(DnsQuestionRecord question, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 5027
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass93_0.<<InternalCachedResolveQueryAsync>b__0>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 5154
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.ResolveQueryAsync(DnsQuestionRecord question, Func`2 resolveAsync) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4285
   at TechnitiumLibrary.Net.Dns.DnsClient.InternalCachedResolveQueryAsync(DnsQuestionRecord question, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 5136
   at DnsServerCore.Dns.DnsServer.DefaultRecursiveResolveAsync(DnsQuestionRecord question, NetworkAddress eDnsClientSubnet, IDnsCache dnsCache, Boolean dnssecValidation, Boolean skipDnsAppAuthoritativeRequestHandlers, CancellationToken cancellationToken) in Z:\Technitium\Projects\DnsServer\DnsServerCore\Dns\DnsServer.cs:line 5256
   at DnsServerCore.Dns.DnsServer.RecursiveResolverBackgroundTaskAsync(DnsQuestionRecord question, NetworkAddress eDnsClientSubnet, Boolean advancedForwardingClientSubnet, IReadOnlyList`1 conditionalForwarders, Boolean dnssecValidation, Boolean cachePrefetchOperation, Boolean cacheRefreshOperation, Boolean skipDnsAppAuthoritativeRequestHandlers, TaskCompletionSource`1 taskCompletionSource) in Z:\Technitium\Projects\DnsServer\DnsServerCore\Dns\DnsServer.cs:line 5039

[2026-07-29 06:43:16 Local] DNS Server failed to resolve the request 'oneapp.mbhbank.hu. A IN' using forwarders: 193.110.56.8, 193.110.57.4.
System.Net.Sockets.SocketException (111): Connection refused
   at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.System.Threading.Tasks.Sources.IValueTaskSource.GetResult(Int16 token)
   at TechnitiumLibrary.Net.Dns.ClientConnection.TcpClientConnection.GetConnectionAsync(CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\ClientConnection\TcpClientConnection.cs:line 182
   at TechnitiumLibrary.Net.Dns.ClientConnection.TcpClientConnection.SendDnsDatagramAsync(DnsDatagram request, Int32 timeout, Transaction transaction, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\ClientConnection\TcpClientConnection.cs:line 262
   at TechnitiumLibrary.Net.Dns.ClientConnection.TcpClientConnection.QueryAsync(DnsDatagram request, Int32 timeout, Int32 retries, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\ClientConnection\TcpClientConnection.cs:line 366
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass89_0.<<InternalResolveAsync>g__DoResolveAsync|1>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4566
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass89_0.<<InternalResolveAsync>g__DoResolveAsync|1>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4792
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass89_0.<<InternalResolveAsync>g__DoResolveAsync|1>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4482
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.InternalResolveAsync(DnsDatagram request, Func`3 getValidatedResponseAsync, Boolean doNotReorderNameServers, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4941
   at TechnitiumLibrary.Net.Dns.DnsClient.InternalResolveAsync(DnsDatagram request, Func`3 getValidatedResponseAsync, Boolean doNotReorderNameServers, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4883
   at TechnitiumLibrary.Net.Dns.DnsClient.GetDnsKeyForAsync(IReadOnlyList`1 lastDSRecords, DnsClient dnsClient, IDnsCache cache, UInt16 udpPayloadSize, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 3314
   at TechnitiumLibrary.Net.Dns.DnsClient.FindDnsKeyForAsync(String ownerName, DnsClass class, IReadOnlyList`1 currentDnsKeyRecords, DnsClient dnsClient, IDnsCache cache, UInt16 udpPayloadSize, DnsDatagram originalResponse, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 3284
   at TechnitiumLibrary.Net.Dns.DnsClient.DnssecValidateResponseAsync(DnsDatagram response, IReadOnlyList`1 lastDSRecords, DnsClient dnsClient, IDnsCache cache, UInt16 udpPayloadSize, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 2780
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass91_0.<<InternalDnssecResolveAsync>b__0>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 5056
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass89_0.<<InternalResolveAsync>g__DoResolveAsync|1>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4623
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass89_0.<<InternalResolveAsync>g__DoResolveAsync|1>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4792
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass89_0.<<InternalResolveAsync>g__DoResolveAsync|1>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4482
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.InternalResolveAsync(DnsDatagram request, Func`3 getValidatedResponseAsync, Boolean doNotReorderNameServers, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4941
   at TechnitiumLibrary.Net.Dns.DnsClient.InternalResolveAsync(DnsDatagram request, Func`3 getValidatedResponseAsync, Boolean doNotReorderNameServers, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4883
   at TechnitiumLibrary.Net.Dns.DnsClient.InternalDnssecResolveAsync(DnsQuestionRecord question, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 5027
   at TechnitiumLibrary.Net.Dns.DnsClient.<>c__DisplayClass93_0.<<InternalCachedResolveQueryAsync>b__0>d.MoveNext() in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 5154
--- End of stack trace from previous location ---
   at TechnitiumLibrary.Net.Dns.DnsClient.ResolveQueryAsync(DnsQuestionRecord question, Func`2 resolveAsync) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 4285
   at TechnitiumLibrary.Net.Dns.DnsClient.InternalCachedResolveQueryAsync(DnsQuestionRecord question, CancellationToken cancellationToken) in Z:\Technitium\Projects\TechnitiumLibrary\TechnitiumLibrary.Net\Dns\DnsClient.cs:line 5136
   at DnsServerCore.Dns.DnsServer.DefaultRecursiveResolveAsync(DnsQuestionRecord question, NetworkAddress eDnsClientSubnet, IDnsCache dnsCache, Boolean dnssecValidation, Boolean skipDnsAppAuthoritativeRequestHandlers, CancellationToken cancellationToken) in Z:\Technitium\Projects\DnsServer\DnsServerCore\Dns\DnsServer.cs:line 5256
   at DnsServerCore.Dns.DnsServer.RecursiveResolverBackgroundTaskAsync(DnsQuestionRecord question, NetworkAddress eDnsClientSubnet, Boolean advancedForwardingClientSubnet, IReadOnlyList`1 conditionalForwarders, Boolean dnssecValidation, Boolean cachePrefetchOperation, Boolean cacheRefreshOperation, Boolean skipDnsAppAuthoritativeRequestHandlers, TaskCompletionSource`1 taskCompletionSource) in Z:\Technitium\Projects\DnsServer\DnsServerCore\Dns\DnsServer.cs:line 5039

Those sites work without issues when trying to reach them from the same network with DNS set to the ones that my Technitium setup uses as upstream.

[ShreyasZare]

Thanks for the post. The forwarders 193.110.56.8, 193.110.57.4 do not have TCP port 53 open which is causing this issue. The reason that the issue comes only with Technitium is that it does DNSSEC validation and the DNSKEY response in there does not fit in UDP packet and thus the DNS server is attempting to retry over TCP which fails with Connection refused as the port is closed.

When you use those forwarders directly, you are not doing DNSSEC validation so it resolves without issues.

If those forwarders are your own servers, you need to make sure that TCP port 53 is open. Or use some other forwarders. There is option to disable DNSSEC validation to fix this but its not recommended to do so.

[Cyberbeni]

Those are my ISP's DNS servers.

[ShreyasZare]

Those are my ISP's DNS servers.

Raise a ticket with them. TCP is mandatory for DNS protocol. If a response does not fit in UDP, the full data can be queries only with TCP. In such case, the domain will fail to resolve when TCP is not available.

This is not just for DNSSEC validation, it can cause a domain name to fail to resolve if it has too many records response which does not fit in UDP packet.

[Apachez-]

Or unless your ISP is blocking DNS queries then disable forwarding and only have resolving cache enabled.

This way your technitium/dns-server will resolve the entries on its own and cache the result without being dependent on broken resolvers at your ISP.

Some suggestions on how to configure Settings -> Cache:

#2070 (comment)

[Cyberbeni]

nc agrees that tcp is not available:

> nc -z -v -u 193.110.56.8 53
Connection to 193.110.56.8 53 port [udp/domain] succeeded!
> nc -z -v 193.110.56.8 53   
nc: connect to 193.110.56.8 port 53 (tcp) failed: Connection refused
> nc -z -v 193.110.57.4 53
nc: connect to 193.110.57.4 port 53 (tcp) failed: Connection refused
> nc -z -v -u 193.110.57.4 53
Connection to 193.110.57.4 53 port [udp/domain] succeeded!

I messaged my ISP about it.