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IPWorks 2022 .NET Edition

Version 22.0 [Build 8171]

DNS Component

Properties   Methods   Events   Configuration Settings   Errors  

The DNS component is used to query DNS for record information.

Syntax

nsoftware.IPWorks.Dns

Remarks

The DNS component queries a DNS server for records as specified in RFC 1035 and other relevant RFCs. The component property QueryType indicates the record to be queried. Calling Query will initiate the query.

Once the query is complete, a single Response event will fire and the record properties will be filled. StatusCode is the server's success or fail code, and Status is a standard string interpretation of the code.

The records are contained in the Records collection. The programming interface is designed to allow a full walk of the records in the DNS response, including provisions for handling new record types.

The component operates synchronously by default (i.e., it waits for a response before returning control to the caller); however, the component also may operate asynchronously (i.e., return control immediately), by setting Timeout to 0. Please see the Timeout property for more information.

Property List


The following is the full list of the properties of the component with short descriptions. Click on the links for further details.

DNSPortThis is the port to connect to on the DNS server.
DNSServerThis is the address of the DNS server.
IdleThe current status of the component.
LocalHostThe name of the local host or user-assigned IP interface through which connections are initiated or accepted.
ProtocolThis protocol is used for the DNS request.
QueryTypeThis is the type of record to query.
RecordsThis is the collection of records in the last response.
RecordSourceThe source of records provided in the Records properties.
RecursiveThis determines whether to ask the DNSServer to recursively query other servers.
RequestIdThis is the Id of the current DNS request.
StatusThis is a standard string interpretation of StatusCode .
StatusCodeThis contains the success or error code for the DNS query.
TimeoutA timeout for the component.

Method List


The following is the full list of the methods of the component with short descriptions. Click on the links for further details.

ConfigSets or retrieves a configuration setting.
DoEventsProcesses events from the internal message queue.
GetFieldValueThis gets the value of the field indicated from a record.
InterruptInterrupt the current method.
QueryThis method queries a domain.
ResetReset the component.

Event List


The following is the full list of the events fired by the component with short descriptions. Click on the links for further details.

ErrorInformation about errors during data delivery.
LogThis event fires once for each log message.
ResponseThis event fires after a DNS query.
SSLServerAuthenticationThis event fires when connecting to the server.
SSLStatusThis shows the progress of the secure connection.

Configuration Settings


The following is a list of configuration settings for the component with short descriptions. Click on the links for further details.

ConnectionModeSets the connection mode for the DNS query.
DNSProtocolLogReturns a 'nslookup' style log.
DoHMethodSpecifies the DNS over HTTPS method.
ResponseTruncatedWhether the response is truncated.
UseIDNsWhether to encode hostnames to internationalized domain names.
CaptureIPPacketInfoUsed to capture the packet information.
DelayHostResolutionWhether the hostname is resolved when RemoteHost is set.
DestinationAddressUsed to get the destination address from the packet information.
DontFragmentUsed to set the Don't Fragment flag of outgoing packets.
LocalHostThe name of the local host through which connections are initiated or accepted.
LocalPortThe port in the local host where the component binds.
MaxPacketSizeThe maximum length of the packets that can be received.
QOSDSCPValueUsed to specify an arbitrary QOS/DSCP setting (optional).
QOSTrafficTypeUsed to specify QOS/DSCP settings (optional).
ShareLocalPortIf set to True, allows more than one instance of the component to be active on the same local port.
UseConnectionDetermines whether to use a connected socket.
UseIPv6Whether or not to use IPv6.
AbsoluteTimeoutDetermines whether timeouts are inactivity timeouts or absolute timeouts.
FirewallDataUsed to send extra data to the firewall.
InBufferSizeThe size in bytes of the incoming queue of the socket.
OutBufferSizeThe size in bytes of the outgoing queue of the socket.
BuildInfoInformation about the product's build.
GUIAvailableTells the component whether or not a message loop is available for processing events.
LicenseInfoInformation about the current license.
UseInternalSecurityAPITells the component whether or not to use the system security libraries or an internal implementation.

DNSPort Property (DNS Component)

This is the port to connect to on the DNS server.

Syntax

public int DNSPort { get; set; }
Public Property DNSPort As Integer

Default Value

53

Remarks

This property contains the port to connect to on the DNS server. A valid port number (a value between 1 and 65535) is required for the connection to take place. The property must be set before a connection is attempted and cannot be changed once a connection is established. Any attempt to change this property while connected will fail with an error.

This property is not available at design time.

DNSServer Property (DNS Component)

This is the address of the DNS server.

Syntax

public string DNSServer { get; set; }
Public Property DNSServer As String

Default Value

""

Remarks

This property contains the address of the DNS server. The component attempts to find the default DNS server for the machine where it is installed, and provide it in the DNSServer property. You may change it to any particular DNS server you want to query. While any internet host running a DNS service will suffice, it is preferable to use either the DNS server for your network or the DNS server for the domain that you are querying.

If the component cannot determine the default DNS server address, the property value will be an empty string.

Note: Automatic discovery of the default DNS server is not supported in the Java edition.

This property is not available at design time.

Idle Property (DNS Component)

The current status of the component.

Syntax

public bool Idle { get; }
Public ReadOnly Property Idle As Boolean

Default Value

True

Remarks

Idle will be False if the component is currently busy (communicating and/or waiting for an answer), and True at all other times.

This property is read-only.

LocalHost Property (DNS Component)

The name of the local host or user-assigned IP interface through which connections are initiated or accepted.

Syntax

public string LocalHost { get; set; }
Public Property LocalHost As String

Default Value

""

Remarks

The LocalHost property contains the name of the local host as obtained by the gethostname() system call, or if the user has assigned an IP address, the value of that address.

In multi-homed hosts (machines with more than one IP interface) setting LocalHost to the value of an interface will make the component initiate connections (or accept in the case of server components) only through that interface.

If the component is connected, the LocalHost property shows the IP address of the interface through which the connection is made in internet dotted format (aaa.bbb.ccc.ddd). In most cases, this is the address of the local host, except for multi-homed hosts (machines with more than one IP interface).

NOTE: LocalHost is not persistent. You must always set it in code, and never in the property window.

Protocol Property (DNS Component)

This protocol is used for the DNS request.

Syntax

public DnsProtocols Protocol { get; set; }

enum DnsProtocols { ptUDP, ptTCP, ptTLS, ptHTTPS }
Public Property Protocol As DnsProtocols

Enum DnsProtocols ptUDP ptTCP ptTLS ptHTTPS End Enum

Default Value

0

Remarks

This property specifies the protocol used for the DNS request when Query is called. Possible values include the following:

0 (ptUDP - default) UDP is used. This is the most commonly used DNS protocol.
1 (ptTCP) TCP is used.
2 (ptTLS) TCP with TLS is used. Set DNSPort to the port that the server uses for TLS connections. Typically this is port 853.
3 (ptHTTPS) HTTP is used. The DNS request is made over HTTP. DNSServer must be set to a URL of a server accepting DNS over HTTPS (DoH) requests. See the DoHMethod configuration setting for additional options when using this protocol.

QueryType Property (DNS Component)

This is the type of record to query.

Syntax

public DnsQueryTypes QueryType { get; set; }

enum DnsQueryTypes { qtAddress, qtNS, qtMD, qtMF, qtCName, qtSOA, qtMailBox, qtMailGroup, qtMR, qtNULL, qtWKS, qtPointer, qtHostInfo, qtMailInfo, qtMX, qtText, qtRP, qtAFSDB, qtX25, qtISDN, qtRT, qtAAAA, qtSRV, qtNAPTR, qtCERT, qtRevLookup }
Public Property QueryType As DnsQueryTypes

Enum DnsQueryTypes qtAddress qtNS qtMD qtMF qtCName qtSOA qtMailBox qtMailGroup qtMR qtNULL qtWKS qtPointer qtHostInfo qtMailInfo qtMX qtText qtRP qtAFSDB qtX25 qtISDN qtRT qtAAAA qtSRV qtNAPTR qtCERT qtRevLookup End Enum

Default Value

1

Remarks

Before a query is attempted, this property must be set to the desired record type. The records are defined as follows:

qtAddress (1)Address Records
qtNS (2)Name Server Records
qtMD (3)Mail Destination Records
qtMF (4)Mail Forwarder Records
qtCName (5)Canonical Name Records
qtSOA (6)Start Of Authority Records
qtMailBox (7)MailBox Records
qtMailGroup (8)Mail Group Records
qtMR (9)MailBox Rename Records
qtNULL (10)NULL Records
qtWKS (11)Well-Known Services Records
qtPointer (12)Pointer Records
qtHostInfo (13)Host Information Records
qtMailInfo (14)Mail Information Records
qtMX (15)Mail Exchange Records
qtText (16)Text Records
qtRP (17)Responsible Person Records
qtAFSDB (18)Service Records
qtX25 (19)X25 Records
qtISDN (20)ISDN Records
qtRT (21)Route Through Records
qtAAAA (28)AAAA Record
qtSRV (33)SRV Record (location of services)
qtNAPTR (35)NAPTR Record (Naming Authority Pointer)
qtCERT (37)Certificate Record (e.g., Stores PKIX, SPKI, PGP)
qtRevLookup (100)Reverse Lookup (Reverse Lookup)

This property is not available at design time.

Records Property (DNS Component)

This is the collection of records in the last response.

Syntax

public DNSRecordList Records { get; }
Public ReadOnly Property Records As DNSRecordList

Remarks

Once the query is complete, a single Response event will fire. The following properties will contain the results:

StatusCodeThe success or error code of the DNS query.
StatusA standard string interpretation of StatusCode.
RecordsThe Records in the last DNS response.
RecordSourceThe source (type) of records being listed.

This collection is indexed from 0 to Count - 1.

Example (loop through all fields of all records)

For i = 0 to DNSControl.Records.Count - 1 For j = 0 to DNSControl.Records.FieldCount(i) - 1 DNSControl.Records(i).FieldIndex = j DoSomethingWith(DNSControl.Records(i).FieldName, DNSControl.Records(i).FieldValue) Next j Next i

This property is read-only and not available at design time.

RecordSource Property (DNS Component)

The source of records provided in the Records properties.

Syntax

public DnsRecordSources RecordSource { get; set; }

enum DnsRecordSources { rsAnswerSection, rsNameServerSection, rsAdditionalRecordsSection }
Public Property RecordSource As DnsRecordSources

Enum DnsRecordSources rsAnswerSection rsNameServerSection rsAdditionalRecordsSection End Enum

Default Value

0

Remarks

This property contains the source of records provided in the Records collection and can have one of the following values:

rsAnswerSection (0)Records answering the question/query.
rsNameServerSection (1)Records pointing toward an authoritative name server.
rsAdditionalRecordsSection (2)Records holding additional information.

This property is not available at design time.

Recursive Property (DNS Component)

This determines whether to ask the DNSServer to recursively query other servers.

Syntax

public bool Recursive { get; set; }
Public Property Recursive As Boolean

Default Value

True

Remarks

If this property is True, the component will tell the DNS server to perform the query recursively. This means that if the DNS server does not have information about the domain being queried, it will send the request to another DNS server.

This property is not available at design time.

RequestId Property (DNS Component)

This is the Id of the current DNS request.

Syntax

public int RequestId { get; set; }
Public Property RequestId As Integer

Default Value

1

Remarks

This property is the identifier of the request that generated the current response values. Each time the component makes a DNS query, it generates a unique request identifier to track the response.

If a custom value is needed for RequestId, the property must be set before sending a request. The component increments RequestId automatically after sending each request.

Note: The component throws an exception when a value that is not between 1 and 32,767 is specified.

This property is not available at design time.

Status Property (DNS Component)

This is a standard string interpretation of StatusCode .

Syntax

public string Status { get; }
Public ReadOnly Property Status As String

Default Value

""

Remarks

This property contains a standard string interpretation of StatusCode. For a list of valid error codes and their descriptions, please see the Error Codes section.

This property is read-only and not available at design time.

StatusCode Property (DNS Component)

This contains the success or error code for the DNS query.

Syntax

public int StatusCode { get; }
Public ReadOnly Property StatusCode As Integer

Default Value

0

Remarks

This property contains the success or error code for the DNS query. For a list of valid error codes and their descriptions, please see the Error Codes section.

This property is read-only and not available at design time.

Timeout Property (DNS Component)

A timeout for the component.

Syntax

public int Timeout { get; set; }
Public Property Timeout As Integer

Default Value

60

Remarks

If the Timeout property is set to 0, all operations return immediately, potentially failing with a WOULDBLOCK error if data cannot be sent immediately.

If Timeout is set to a positive value, data is sent in a blocking manner and the component will wait for the operation to complete before returning control. The component will handle any potential WOULDBLOCK errors internally and automatically retry the operation for a maximum of Timeout seconds.

The component will use DoEvents to enter an efficient wait loop during any potential waiting period, making sure that all system events are processed immediately as they arrive. This ensures that the host application does not "freeze" and remains responsive.

If Timeout expires, and the operation is not yet complete, the component throws an exception.

Please note that by default, all timeouts are inactivity timeouts, i.e. the timeout period is extended by Timeout seconds when any amount of data is successfully sent or received.

The default value for the Timeout property is 60 seconds.

Config Method (DNS Component)

Sets or retrieves a configuration setting.

Syntax

public string Config(string configurationString);

Async Version
public async Task<string> Config(string configurationString);
public async Task<string> Config(string configurationString, CancellationToken cancellationToken);
Public Function Config(ByVal ConfigurationString As String) As String

Async Version
Public Function Config(ByVal ConfigurationString As String) As Task(Of String)
Public Function Config(ByVal ConfigurationString As String, cancellationToken As CancellationToken) As Task(Of String)

Remarks

Config is a generic method available in every component. It is used to set and retrieve configuration settings for the component.

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the component, access to these internal properties is provided through the Config method.

To set a configuration setting named PROPERTY, you must call Config("PROPERTY=VALUE"), where VALUE is the value of the setting expressed as a string. For boolean values, use the strings "True", "False", "0", "1", "Yes", or "No" (case does not matter).

To read (query) the value of a configuration setting, you must call Config("PROPERTY"). The value will be returned as a string.

DoEvents Method (DNS Component)

Processes events from the internal message queue.

Syntax

public void DoEvents();
Public Sub DoEvents()

Remarks

When DoEvents is called, the component processes any available events. If no events are available, it waits for a preset period of time, and then returns.

GetFieldValue Method (DNS Component)

This gets the value of the field indicated from a record.

Syntax

public string GetFieldValue(int recordIndex, string fieldName);

Async Version
public async Task<string> GetFieldValue(int recordIndex, string fieldName);
public async Task<string> GetFieldValue(int recordIndex, string fieldName, CancellationToken cancellationToken);
Public Function GetFieldValue(ByVal RecordIndex As Integer, ByVal FieldName As String) As String

Async Version
Public Function GetFieldValue(ByVal RecordIndex As Integer, ByVal FieldName As String) As Task(Of String)
Public Function GetFieldValue(ByVal RecordIndex As Integer, ByVal FieldName As String, cancellationToken As CancellationToken) As Task(Of String)

Remarks

This method will get the value of the DNS record field specified by FieldName from the DNS record at RecordIndex. If no such field exists for that record type, the component throws an exception.

Interrupt Method (DNS Component)

Interrupt the current method.

Syntax

public void Interrupt();

Async Version
public async Task Interrupt();
public async Task Interrupt(CancellationToken cancellationToken);
Public Sub Interrupt()

Async Version
Public Sub Interrupt() As Task
Public Sub Interrupt(cancellationToken As CancellationToken) As Task

Remarks

If there is no method in progress, Interrupt simply returns, doing nothing.

Query Method (DNS Component)

This method queries a domain.

Syntax

public void Query(string domain);

Async Version
public async Task Query(string domain);
public async Task Query(string domain, CancellationToken cancellationToken);
Public Sub Query(ByVal Domain As String)

Async Version
Public Sub Query(ByVal Domain As String) As Task
Public Sub Query(ByVal Domain As String, cancellationToken As CancellationToken) As Task

Remarks

This method will query the host Domain for any records of the type in QueryType. After the query, RequestId is the identifier corresponding to the request. Once the query is complete, a single Response event will fire. The following properties will contain the results:

StatusCodeThe success or error code of the DNS query.
StatusA standard string interpretation of StatusCode.
RecordsThe Records in the last DNS response.
RecordSourceThe source (type) of records being listed.

Reset Method (DNS Component)

Reset the component.

Syntax

public void Reset();

Async Version
public async Task Reset();
public async Task Reset(CancellationToken cancellationToken);
Public Sub Reset()

Async Version
Public Sub Reset() As Task
Public Sub Reset(cancellationToken As CancellationToken) As Task

Remarks

This method will reset the component's properties to their default values.

Error Event (DNS Component)

Information about errors during data delivery.

Syntax

public event OnErrorHandler OnError;

public delegate void OnErrorHandler(object sender, DnsErrorEventArgs e);

public class DnsErrorEventArgs : EventArgs {
  public int ErrorCode { get; }

  public string Description { get; }

}
Public Event OnError As OnErrorHandler

Public Delegate Sub OnErrorHandler(sender As Object, e As DnsErrorEventArgs)

Public Class DnsErrorEventArgs Inherits EventArgs
  Public ReadOnly Property ErrorCode As Integer

  Public ReadOnly Property Description As String

End Class

Remarks

The Error event is fired in case of exceptional conditions during message processing. Normally the component throws an exception.

ErrorCode contains an error code and Description contains a textual description of the error. For a list of valid error codes and their descriptions, please refer to the Error Codes section.

Log Event (DNS Component)

This event fires once for each log message.

Syntax

public event OnLogHandler OnLog;

public delegate void OnLogHandler(object sender, DnsLogEventArgs e);

public class DnsLogEventArgs : EventArgs {
  public int LogLevel { get; }

  public string Message { get; }

  public string LogType { get; }

}
Public Event OnLog As OnLogHandler

Public Delegate Sub OnLogHandler(sender As Object, e As DnsLogEventArgs)

Public Class DnsLogEventArgs Inherits EventArgs
  Public ReadOnly Property LogLevel As Integer

  Public ReadOnly Property Message As String

  Public ReadOnly Property LogType As String

End Class

Remarks

TBD

Response Event (DNS Component)

This event fires after a DNS query.

Syntax

public event OnResponseHandler OnResponse;

public delegate void OnResponseHandler(object sender, DnsResponseEventArgs e);

public class DnsResponseEventArgs : EventArgs {
  public int RequestId { get; }

  public string Domain { get; }

  public int StatusCode { get; }

  public string Description { get; }

  public bool Authoritative { get; }

}
Public Event OnResponse As OnResponseHandler

Public Delegate Sub OnResponseHandler(sender As Object, e As DnsResponseEventArgs)

Public Class DnsResponseEventArgs Inherits EventArgs
  Public ReadOnly Property RequestId As Integer

  Public ReadOnly Property Domain As String

  Public ReadOnly Property StatusCode As Integer

  Public ReadOnly Property Description As String

  Public ReadOnly Property Authoritative As Boolean

End Class

Remarks

The Response event will fire after a call to Query. The RequestId parameter contains the request Id associated with the original query. Domain is the domain of the query. The Authoritative parameter is true if the response is from an authoritative name server. If there is an error returned by the server, StatusCode and Description provide them.

Once the query is complete, a single Response event will fire. The following properties will contain the results:

StatusCodeThe success or error code of the DNS query.
StatusA standard string interpretation of StatusCode.
RecordsThe Records in the last DNS response.
RecordSourceThe source (type) of records being listed.

SSLServerAuthentication Event (DNS Component)

This event fires when connecting to the server.

Syntax

public event OnSSLServerAuthenticationHandler OnSSLServerAuthentication;

public delegate void OnSSLServerAuthenticationHandler(object sender, DnsSSLServerAuthenticationEventArgs e);

public class DnsSSLServerAuthenticationEventArgs : EventArgs {
  public string RemoteAddress { get; }

  public int RemotePort { get; }

  public string CertEncoded { get; }
public byte[] CertEncodedB { get; } public string CertSubject { get; } public string CertIssuer { get; } public string Status { get; } public bool Accept { get; set; } }
Public Event OnSSLServerAuthentication As OnSSLServerAuthenticationHandler

Public Delegate Sub OnSSLServerAuthenticationHandler(sender As Object, e As DnsSSLServerAuthenticationEventArgs)

Public Class DnsSSLServerAuthenticationEventArgs Inherits EventArgs
  Public ReadOnly Property RemoteAddress As String

  Public ReadOnly Property RemotePort As Integer

  Public ReadOnly Property CertEncoded As String
Public ReadOnly Property CertEncodedB As Byte() Public ReadOnly Property CertSubject As String Public ReadOnly Property CertIssuer As String Public ReadOnly Property Status As String Public Property Accept As Boolean End Class

Remarks

This event allows the client to decide whether or not to continue with the connection process. The Accept parameter recommends whether to continue or close the connection. This is just a suggestion: application software must use its own logic to determine whether or not to continue.

When Accept is False, Status shows why the verification failed (otherwise, Status contains the string "OK"). If the client decides to continue, you can override and accept the certificate by setting the Accept parameter to True.

RemoteAddress is the IP address of the server.

RemotePort is the source port of the server.

CertEncoded is the Base64-encoded certificate presented by the server.

CertSubject is the subject of the certificate presented by the server.

CertIssuer is the subject of the issuer of the certificate presented by the server.

Status is the status of the certificate.

Accept defines whether the certificate is accepted.

SSLStatus Event (DNS Component)

This shows the progress of the secure connection.

Syntax

public event OnSSLStatusHandler OnSSLStatus;

public delegate void OnSSLStatusHandler(object sender, DnsSSLStatusEventArgs e);

public class DnsSSLStatusEventArgs : EventArgs {
  public string RemoteAddress { get; }

  public int RemotePort { get; }

  public string Message { get; }

}
Public Event OnSSLStatus As OnSSLStatusHandler

Public Delegate Sub OnSSLStatusHandler(sender As Object, e As DnsSSLStatusEventArgs)

Public Class DnsSSLStatusEventArgs Inherits EventArgs
  Public ReadOnly Property RemoteAddress As String

  Public ReadOnly Property RemotePort As Integer

  Public ReadOnly Property Message As String

End Class

Remarks

The event is fired for informational and logging purposes only. It is used to track the progress of the connection.

RemoteAddress is the IP address of the remote machine.

RemotePort is the port of the remote machine.

Message is the log message.

DNSRecord Type

This is a record that is returned by the DNS server.

Remarks

When a Query method is performed by the DNS component, the DNS server returns one or more DNSRecords containing information about the domain you specified. This information is contained in the different fields of the record.

Each record may have multiple FieldNames and corresponding FieldValues. You may iterate through these by setting the FieldIndex field.

Fields

Domain
String

This field contains the domain name associated with the selected response record, at RecordIndex.

FieldCount
Integer

This field contains the number of fields in the current record.

After a successful query, the field values for each record will be provided in the Records collection.

To retrieve a particular field value for a record, first set FieldIndex to a valid response field index and then query records collection for the value of that field.

FieldIndex
Integer

This field contains the index of the selected field of the current record. FieldIndex valid values are from 0 to (FieldCount -1).

After a successful query, the field values for each record will be provided in the Records collection.

To retrieve a particular field value for a record, first set FieldIndex to a valid response field index and then query records collection for the value of that field.

FieldName
String

This field contains the name of the field selected by FieldIndex. Field names are different depending on the record type. For example, an MX record type will contain two fields: PREFERENCE and EXCHANGE, but an SOA record type contains seven fields.

Field names:

A Records ADDRESS
NS RecordsDNAME
MDMADNAME
MFMADNAME
CNAMECNAME
SOAMNAME
SOARNAME
SOASERIAL
SOAREFRESH
SOARETRY
SOAEXPIRE
SOAMINIMUM
MBMADNAME
MGMGMNAME
MRNEWNAME
NULLNULL
WKSADDRESS
WKSPROTOCOL
WKSSERVICEMAP
PTRPTRDNAME
HINFOCPU
HINFOOS
MINFORMAILBX
MINFOEMAILBX
MXPREFERENCE
MXEXCHANGE
TXTTXT
RPMBOXDNAME
RPTXTDNAME
AFSDBSUBTYPE
AFSDBHOSTNAME
X25PSDNADDRESS
ISDNISDNADDRESS
RTPREFERENCE
RTINTERMEDIATE
AAAAADDRESS
SRVPRIORITY
SRVWEIGHT
SRVPORT
SRVTARGET
NAPTRORDER
NAPTRPRIORITY
NAPTRFLAGS
NAPTRSERVICES
NAPTRREGEXP
NAPTRREPLACEMENT

FieldValue
String

This field contains the value of the field selected by FieldIndex.

After a successful query, the field values for each record will be provided in the Records collection.

To retrieve a particular field value for a record, first set FieldIndex to a valid response field index and then query records collection for the value of that field.

FieldValueB
Byte []

This field contains the value of the field selected by FieldIndex.

After a successful query, the field values for each record will be provided in the Records collection.

To retrieve a particular field value for a record, first set FieldIndex to a valid response field index and then query records collection for the value of that field.

RecordData
String

This field contains the full record data as received from the DNS server.

After a successful query, the field values for each record will be provided in the Records collection.

To retrieve a particular field value for a record, first set FieldIndex to a valid response field index and then query records collection for the value of that field.

RecordDataB
Byte []

This field contains the full record data as received from the DNS server.

After a successful query, the field values for each record will be provided in the Records collection.

To retrieve a particular field value for a record, first set FieldIndex to a valid response field index and then query records collection for the value of that field.

RecordType
DNSRecordTypes

This field contains the record type.

Record types correspond to QueryType and are defined as follows:

rtAddress (1)Address Record
rtNS (2)Name Server Record
rtMD (3)Mail Destination Record
rtMF (4)Mail Forwarder Record
rtCName (5)Canonical Name Record
rtSOA (6)Start of Authority Record
rtMailBox (7)MailBox Record
rtMailGroup (8)Mail Group Record
rtMR (9)MailBox Rename Record
rtNULL (10)NULL Record
rtWKS (11)Well-Known Services Record
rtPointer (12)Pointer Record
rtHostInfo (13)Host Information Record
rtMailInfo (14)Mail Information Record
rtMX (15)Mail Exchange Record
rtText (16)Text Record
rtRP (17)Responsible Person Record
rtAFSDB (18)Service Record
rtX25 (19)X25 Record
rtISDN (20)ISDN Record
rtRT (21)Route Through Record
rtAAAA (28)AAAA Record
rtSRV (33)SRV Record (Location of Services)
rtNAPTR (35)Naming Authority Pointer Record

RecordTypeName
String

This field contains the string representation of the current record type defined by RecordType.

A (1)Address Record
NS (2)Name Server Record
MD (3)Mail Destination Record
MF (4)Mail Forwarder Record
CName (5)Canonical Name Record
SOA (6)Start of Authority Record
MB (7)MailBox Record
MG (8)Mail Group Record
MR (9)MailBox Rename Record
NULL (10)NULL Record
WKS (11)Well-Known Services Record
PTR (12)Pointer Record
HINFO (13)Host Information Record
MINFO (14)Mail Information Record
MX (15)Mail Exchange Record
TXT (16)Text Record
RP (17)Responsible Person Record
AFSDB (18)Service Record
X25 (19)X25 Record
ISDN (20)ISDN Record
RT (21)Route Through Record
AAAA (28)AAAA Record
rtSRV (33)SRV Record (Location of Services)
NAPTR (35)Naming Authority Pointer Record

TTL
Integer

This field contains the record Time to Live (TTL) value. The TTL specifies the time interval in seconds that the record is valid, or the time interval that the record can be cached before the DNS server should be queried again.

Constructors

public DNSRecord();
Public DNSRecord()

Configuration Settings (DNS Component)

The component accepts one or more of the following configuration settings. Configuration settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the component, access to these internal properties is provided through the Config method.

DNS Configuration Settings

ConnectionMode:   Sets the connection mode for the DNS query.

This setting may be used to configure the connection mode (TCP or UDP) for the component.

The appropriate values are as follows:

0Auto-connection mode. Try UDP first, and if needed, retry with TCP automatically.
1Always use UDP for queries (default setting).
2Always use TCP for queries. Note: the DNS server must support TCP queries or this will fail.

DNSProtocolLog:   Returns a 'nslookup' style log.

This setting may be used to obtain a "nslookup" style log from the component. It must be enabled before calling Query and then must be queried after the operation is complete. For instance: DNS.Config("DNSProtocolLog=true"); DNS.Query("www.nsoftware.com"); string myLog = DNS.Config("DNSProtocolLog"); The default value is False and no log will be constructed.

DoHMethod:   Specifies the DNS over HTTPS method.

This setting may be used to configure the method used when performing DNS over HTTPS (DoH). Possible values are as follows:

0 (default)HTTP POST (DNS Wireformat)
1HTTP GET (DNS Wireformat)
2HTTP GET (JSON)

This setting is applicable only when Protocol is set to ptHTTPS.

ResponseTruncated:   Whether the response is truncated.

This setting may be queried after calling Query to determine if the response from thet DNSServer is truncated. If the response is large and cannot be transferred over UDP, the server may truncate the response. When this setting is True the response is truncated and the request should be attempted again over a different Protocol, such as ptTCP.

UseIDNs:   Whether to encode hostnames to internationalized domain names.

This setting specifies whether hostnames containing non-ASCII characters are encoded to internationalized domain names. When set to True if a hostname contains non-ASCII characters it is encoded using Punycode to an IDN.

The default value is False and the hostname will always be used exactly as specified.

UDPPort Configuration Settings

CaptureIPPacketInfo:   Used to capture the packet information.

If this is set to true, the component will capture the IP packet information.

The default value for this setting is False.

Note: This setting is only available in Windows.

DelayHostResolution:   Whether the hostname is resolved when RemoteHost is set.

This setting specifies whether a hostname is resolved immediately when RemoteHost is set. If true the component will resolve the hostname and the IP address will be present in the RemoteHost property. If false, the hostname is not resolved until needed by the component when a method to connect or send data is called. If desired, ResolveRemoteHost may called to manually resolve the value in RemoteHost at any time.

The default value is false for the default library and true for the Async library. The default value is false.

DestinationAddress:   Used to get the destination address from the packet information.

If CaptureIPPacketInfo is set to true, then this will be populated with the packet's destination address when a packet is received. This information will be accessible in the DataIn event.

Note: This setting is only available in Windows.

DontFragment:   Used to set the Don't Fragment flag of outgoing packets.

When set to True, packets sent by the component will have the Don't Fragment flag set. The default value is False.

LocalHost:   The name of the local host through which connections are initiated or accepted.

The LocalHost setting contains the name of the local host as obtained by the gethostname() system call, or if the user has assigned an IP address, the value of that address.

In multi-homed hosts (machines with more than one IP interface) setting LocalHost to the value of an interface will make the component initiate connections (or accept in the case of server components) only through that interface.

If the component is connected, the LocalHost setting shows the IP address of the interface through which the connection is made in internet dotted format (aaa.bbb.ccc.ddd). In most cases, this is the address of the local host, except for multi-homed hosts (machines with more than one IP interface).

LocalPort:   The port in the local host where the component binds.

This must be set before a connection is attempted. It instructs the component to bind to a specific port (or communication endpoint) in the local machine.

Setting this to 0 (default) enables the system to choose a port at random. The chosen port will be shown by LocalPort after the connection is established.

LocalPort cannot be changed once a connection is made. Any attempt to set this when a connection is active will generate an error.

This; setting is useful when trying to connect to services that require a trusted port in the client side. An example is the remote shell (rsh) service in UNIX systems.

MaxPacketSize:   The maximum length of the packets that can be received.

This setting specifies the maximum size of the datagrams that the component will accept without truncation.

QOSDSCPValue:   Used to specify an arbitrary QOS/DSCP setting (optional).

UseConnection must be True to use this setting. This option allows you to specify an arbitrary DSCP value between 0 and 63. The default is 0. When set to the default value the component will not set a DSCP value.

Note: This setting uses the qWAVE API is only available on Windows 7, Windows Server 2008 R2, and later.

QOSTrafficType:   Used to specify QOS/DSCP settings (optional).

UseConnection must be True to use this setting. You may specify either the text or integer values: BestEffort (0), Background (1), ExcellentEffort (2), AudioVideo (3), Voice (4), and Control (5).

Note: This setting uses the qWAVE API which is only available on Windows Vista and Windows Server 2008 or above.

Note: QOSTrafficType must be set before setting Active to true.

ShareLocalPort:   If set to True, allows more than one instance of the component to be active on the same local port.

This option must be set before the component is activated through the Active property or it will have no effect.

The default value for this setting is False.

UseConnection:   Determines whether to use a connected socket.

UseConnection specifies whether the component should use a connected socket or not. The connection is defined as an association in between the local address/port and the remote address/port. As such, this is not a connection in the traditional TCP sense. What it means is only that the component will send and receive data only to and from the specified destination.

The default value for this setting is False.

UseIPv6:   Whether or not to use IPv6.

By default, the component expects an IPv4 address for local and remote host properties, and will create an IPv4 socket. To use IPv6 instead, set this to True.

Socket Configuration Settings

AbsoluteTimeout:   Determines whether timeouts are inactivity timeouts or absolute timeouts.

If AbsoluteTimeout is set to True, any method which does not complete within Timeout seconds will be aborted. By default, AbsoluteTimeout is False, and the timeout is an inactivity timeout.

Note: This option is not valid for UDP ports.

FirewallData:   Used to send extra data to the firewall.

When the firewall is a tunneling proxy, use this property to send custom (additional) headers to the firewall (e.g. headers for custom authentication schemes).

InBufferSize:   The size in bytes of the incoming queue of the socket.

This is the size of an internal queue in the TCP/IP stack. You can increase or decrease its size depending on the amount of data that you will be receiving. Increasing the value of the InBufferSize setting can provide significant improvements in performance in some cases.

Some TCP/IP implementations do not support variable buffer sizes. If that is the case, when the component is activated the InBufferSize reverts to its defined size. The same happens if you attempt to make it too large or too small.

OutBufferSize:   The size in bytes of the outgoing queue of the socket.

This is the size of an internal queue in the TCP/IP stack. You can increase or decrease its size depending on the amount of data that you will be sending. Increasing the value of the OutBufferSize setting can provide significant improvements in performance in some cases.

Some TCP/IP implementations do not support variable buffer sizes. If that is the case, when the component is activated the OutBufferSize reverts to its defined size. The same happens if you attempt to make it too large or too small.

Base Configuration Settings

BuildInfo:   Information about the product's build.

When queried, this setting will return a string containing information about the product's build.

GUIAvailable:   Tells the component whether or not a message loop is available for processing events.

In a GUI-based application, long-running blocking operations may cause the application to stop responding to input until the operation returns. The component will attempt to discover whether or not the application has a message loop and, if one is discovered, it will process events in that message loop during any such blocking operation.

In some non-GUI applications, an invalid message loop may be discovered that will result in errant behavior. In these cases, setting GUIAvailable to false will ensure that the component does not attempt to process external events.

LicenseInfo:   Information about the current license.

When queried, this setting will return a string containing information about the license this instance of a component is using. It will return the following information:

  • Product: The product the license is for.
  • Product Key: The key the license was generated from.
  • License Source: Where the license was found (e.g., RuntimeLicense, License File).
  • License Type: The type of license installed (e.g., Royalty Free, Single Server).
UseInternalSecurityAPI:   Tells the component whether or not to use the system security libraries or an internal implementation.

By default the component will use the system security libraries to perform cryptographic functions. When set to False calls to unmanaged code will be made. In certain environments this is not desirable. To use a completely managed security implementation set this setting to True. Setting this to True tells the component to use the internal implementation instead of using the system's security API.

Note: This setting is static. The value set is applicable to all components used in the application.

When this value is set the product's system DLL is no longer required as a reference, as all unmanaged code is stored in that file.

Trappable Errors (DNS Component)

DNS Errors

100   No records were found.
220   Invalid record index.
221   Invalid field index for record type.
222   Invalid record source.
223   Unknown record type.
224   Could not determine DNS server address.
225   Could not parse address.

The component may also return one of the following error codes, which are inherited from other components.

UDPPort Errors

104   UDPPort is already Active.
106   You cannot change the LocalPort while the component is Active.
107   You cannot change the LocalHost at this time. A connection is in progress.
109   The component must be Active for this operation.
112   Cannot change MaxPacketSize while the component is Active.
113   Cannot change ShareLocalPort option while the component is Active.
114   Cannot change RemoteHost when UseConnection is set and the component Active.
115   Cannot change RemotePort when UseConnection is set and the component is Active.
116   RemotePort can't be zero when UseConnection is set. Please specify a valid service port number.
117   Cannot change UseConnection while the component is Active.
118   Message can't be longer than MaxPacketSize.
119   Message too short.
434   Unable to convert string to selected CodePage

SSL Errors

270   Cannot load specified security library.
271   Cannot open certificate store.
272   Cannot find specified certificate.
273   Cannot acquire security credentials.
274   Cannot find certificate chain.
275   Cannot verify certificate chain.
276   Error during handshake.
280   Error verifying certificate.
281   Could not find client certificate.
282   Could not find server certificate.
283   Error encrypting data.
284   Error decrypting data.

TCP/IP Errors

10004   [10004] Interrupted system call.
10009   [10009] Bad file number.
10013   [10013] Access denied.
10014   [10014] Bad address.
10022   [10022] Invalid argument.
10024   [10024] Too many open files.
10035   [10035] Operation would block.
10036   [10036] Operation now in progress.
10037   [10037] Operation already in progress.
10038   [10038] Socket operation on non-socket.
10039   [10039] Destination address required.
10040   [10040] Message too long.
10041   [10041] Protocol wrong type for socket.
10042   [10042] Bad protocol option.
10043   [10043] Protocol not supported.
10044   [10044] Socket type not supported.
10045   [10045] Operation not supported on socket.
10046   [10046] Protocol family not supported.
10047   [10047] Address family not supported by protocol family.
10048   [10048] Address already in use.
10049   [10049] Can't assign requested address.
10050   [10050] Network is down.
10051   [10051] Network is unreachable.
10052   [10052] Net dropped connection or reset.
10053   [10053] Software caused connection abort.
10054   [10054] Connection reset by peer.
10055   [10055] No buffer space available.
10056   [10056] Socket is already connected.
10057   [10057] Socket is not connected.
10058   [10058] Can't send after socket shutdown.
10059   [10059] Too many references, can't splice.
10060   [10060] Connection timed out.
10061   [10061] Connection refused.
10062   [10062] Too many levels of symbolic links.
10063   [10063] File name too long.
10064   [10064] Host is down.
10065   [10065] No route to host.
10066   [10066] Directory not empty
10067   [10067] Too many processes.
10068   [10068] Too many users.
10069   [10069] Disc Quota Exceeded.
10070   [10070] Stale NFS file handle.
10071   [10071] Too many levels of remote in path.
10091   [10091] Network subsystem is unavailable.
10092   [10092] WINSOCK DLL Version out of range.
10093   [10093] Winsock not loaded yet.
11001   [11001] Host not found.
11002   [11002] Non-authoritative 'Host not found' (try again or check DNS setup).
11003   [11003] Non-recoverable errors: FORMERR, REFUSED, NOTIMP.
11004   [11004] Valid name, no data record (check DNS setup).

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IPWorks 2022 .NET Edition - Version 22.0 [Build 8171]