Dns C# Reference Documentation

Dns

Current Version: 9.5.0.97

API for managing DNS nameservers to be used by Chilkat, and for doing DNS queries.

Object Creation

Chilkat.Dns obj = new Chilkat.Dns();

Properties

DebugLogFilePath
public string DebugLogFilePath {get; set; }

If set to a file path, causes each Chilkat method or property call to automatically append it's LastErrorText to the specified log file. The information is appended such that if a hang or crash occurs, it is possible to see the context in which the problem occurred, as well as a history of all Chilkat calls up to the point of the problem. The VerboseLogging property can be set to provide more detailed information.

This property is typically used for debugging the rare cases where a Chilkat method call hangs or generates an exception that halts program execution (i.e. crashes). A hang or crash should generally never happen. The typical causes of a hang are:

  1. a timeout related property was set to 0 to explicitly indicate that an infinite timeout is desired,
  2. the hang is actually a hang within an event callback (i.e. it is a hang within the application code), or
  3. there is an internal problem (bug) in the Chilkat code that causes the hang.

top
HeartbeatMs
public int HeartbeatMs {get; set; }
Introduced in version 9.5.0.96

The number of milliseconds between each AbortCheck event callback. The AbortCheck callback allows an application to abort any DNS operation prior to completion. If HeartbeatMs is 0 (the default), no AbortCheck event callbacks will fire.

top
LastErrorHtml
public string LastErrorHtml {get; }

Provides information in HTML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

top
LastErrorText
public string LastErrorText {get; }

Provides information in plain-text format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

top
LastErrorXml
public string LastErrorXml {get; }

Provides information in XML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

top
LastMethodSuccess
public bool LastMethodSuccess {get; set; }

Indicate whether the last method call succeeded or failed. A value of true indicates success, a value of false indicates failure. This property is automatically set for method calls. It is not modified by property accesses. The property is automatically set to indicate success for the following types of method calls:

  • Any method that returns a string.
  • Any method returning a Chilkat object, binary bytes, or a date/time.
  • Any method returning a standard boolean status value where success = true and failure = false.
  • Any method returning an integer where failure is defined by a return value less than zero.

Note: Methods that do not fit the above requirements will always set this property equal to true. For example, a method that returns no value (such as a "void" in C++) will technically always succeed.

top
MaxWaitMs
public int MaxWaitMs {get; set; }
Introduced in version 9.5.0.96

The maxiumum number of milliseconds to wait for the answer to a DNS query. A value of 0 is to wait indefinitely (no timeout). It's not a good idea to specify 0 (infinite timeout) or a value less than 1000 (1 second). The default value is 10000 milliseconds.

top
NumNameservers
public int NumNameservers {get; }
Introduced in version 9.5.0.96

The number of nameservers currently being used by Chilkat for DNS queries in all objects/classes, such as for HTTP, Email, FTP, SSH, etc.

top
TlsPref
public int TlsPref {get; set; }
Introduced in version 9.5.0.96

Specifies the TLS preference. Possible values are:

  • 0 = No TLS
  • 1 = Prefer TLS if possible.
  • 2 = Require TLS

The default value is 0. If TLS is preferred then DNS nameservers with TLS capability will be tried first. If none succeed, then UDP/TCP will be tried. If TLS is required, then only TLS capable nameservers will be tried and all DNS queries will use TLS.

Note: To use TLS, your application needs to first specify nameservers by calling AddNameserver once per nameserver with the supportsTls argument set to true.

top
VerboseLogging
public bool VerboseLogging {get; set; }

If set to true, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is false. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.

top
Version
public string Version {get; }

Version of the component/library, such as "9.5.0.94"

top

Methods

AddDefaultNameservers
public void AddDefaultNameservers();
Introduced in version 9.5.0.96

Adds the default (auto-assigned) nameservers to the collection of nameservers used by Chilkat for DNS queries and domain to IP address lookups.

top
AddNameserver
public void AddNameserver(string ipAddr, bool supportsTls);
Introduced in version 9.5.0.96

Adds a new nameserver to the collection of nameservers used by Chilkat for DNS queries and domain to IP address lookups. The ipAddr specifies the IPv4 address of the nameserver. The supportsTls indicates if the namserver supports DoT (DNS over TLS. DoT uses port 853 for encrypted DNS communication.) If the TlsPreference property is set to 1 or 2, then Chilkat will use TLS nameservers.

top
GetNameserver
public string GetNameserver(int index);
Introduced in version 9.5.0.96

Returns the IP address of the Nth nameserver currently used by Chilkat for DNS queries and domain to IP address lookups. The index specifies the index of the nameserver. The 1st nameserver is at index 0.

Returns null on failure

top
Query
public bool Query(string recordType, string domain, JsonObject answer);
Introduced in version 9.5.0.96

Performs an DNS query for domain and returns the answer in answer. The type of DNS query is specified in recordType and can be A, AAAA, ALIAS, CAA, MX, NS, SOA, TXT. Additional record types can be added as needed.

top
QueryAsync (.NET Core C#) (C#) (Mono C#) (PowerShell)
public Task QueryAsync(string recordType, string domain, JsonObject answer);
Introduced in version 9.5.0.96

Creates an asynchronous task to call the Query method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Note: Async method event callbacks happen in the background thread. Accessing and updating UI elements existing in the main thread may require special considerations.

Returns null on failure

top
RemoveAllNameservers
public void RemoveAllNameservers();
Introduced in version 9.5.0.96

Removes all nameservers from the collection of nameservers used by Chilkat. An application can call this method to reset to 0 nameservers before adding new nameservers. If a DNS domain to IP address resolution is needed by Chilkat, then the auto-assigned nameserver IP addresses will be automaticaly restored.

top
RemoveNameserver
public void RemoveNameserver(string ipAddr);
Introduced in version 9.5.0.96

Removes a nameserver from the collection of nameservers used by Chilkat. The ipAddr is the IPv4 address of the nameserver to be removed.

top

Events

AbortCheck
public event AbortCheckEventHandler OnAbortCheck;

Provides the opportunity for a method call to be aborted. The AbortCheck event is fired periodically based on the value of the HeartbeatMs property. If HeartbeatMs is 0, then no AbortCheck events will fire. As an example, to fire 5 AbortCheck events per second, set the HeartbeatMs property equal to 200.

Chilkat .NET Event Implementation

Args are passed using Chilkat.AbortCheckEventArgs

Event callback implementation:

private void dns_OnAbortCheck(object sender, Chilkat.AbortCheckEventArgs args)
	{
	    // application code goes here.
	}

To add an event handler:

Chilkat.Dns dns = new Chilkat.Dns();
dns.OnAbortCheck += dns_OnAbortCheck;

Chilkat Mono/.NET Core Event Implementation

Event callback implementation:

public void handleAbortCheck(out bool abort)
	{
	    // application code goes here.
	}

To add an event handler:

Chilkat.Dns dns = new Chilkat.Dns();
// ...
Chilkat.Dns.AbortCheck abortCheck = new Chilkat.Dns.AbortCheck(handleAbortCheck);
dns.setAbortCheckCb(abortCheck);
top
PercentDone
public event PercentDoneEventHandler OnPercentDone;

Provides the percentage completed for any method that involves network communications or time-consuming processing (assuming it is a method where a percentage completion can be measured). This event is only fired when it is possible to know a percentage completion, and when it makes sense to express the operation as a percentage completed. The pctDone argument will have a value from 1 to 100. For operations (Chilkat method calls) that complete very quickly, the number of PercentDone callbacks will vary, but the final callback should have a value of 100. For long running operations, no more than one callback per percentage point will occur (for example: 1, 2, 3, ... 98, 99, 100).

The PercentDone callback counts as an AbortCheck event. For method calls that complete quickly such that PercentDone events fire, it may be that AbortCheck events don't fire because the opportunity to abort is already provided in the PercentDone callback. For time consuming operations, where the amount of time between PercentDone callbacks are long, AbortCheck callbacks may be used to allow for the operation to be aborted in a more responsive manner.

The abort output argument provides a means for aborting the operation. Setting it to true will cause the method to abort and return a failed status (or whatever return value indicates failure).

Chilkat .NET Event Implementation

Args are passed using Chilkat.PercentDoneEventArgs

Event callback implementation:

private void dns_OnPercentDone(object sender, Chilkat.PercentDoneEventArgs args)
	{
	    // application code goes here.
	}

To add an event handler:

Chilkat.Dns dns = new Chilkat.Dns();
dns.OnPercentDone += dns_OnPercentDone;

Chilkat Mono/.NET Core Event Implementation

Event callback implementation:

public void handlePercentDone(int pctDone, out bool abort)
	{
	    // application code goes here.
	}

To add an event handler:

Chilkat.Dns dns = new Chilkat.Dns();
// ...
Chilkat.Dns.PercentDone percentDone = new Chilkat.Dns.PercentDone(handlePercentDone);
dns.setPercentDoneCb(percentDone);
top
ProgressInfo
public event ProgressInfoEventHandler OnProgressInfo;

A general name/value event that provides information about what is happening during a method call. To find out what information is available, write code to handle this event and log the name/value pairs. Most are self-explanatory.

Chilkat .NET Event Implementation

Args are passed using Chilkat.ProgressInfoEventArgs

Event callback implementation:

private void dns_OnProgressInfo(object sender, Chilkat.ProgressInfoEventArgs args)
	{
	    // application code goes here.
	}

To add an event handler:

Chilkat.Dns dns = new Chilkat.Dns();
dns.OnProgressInfo += dns_OnProgressInfo;

Chilkat Mono/.NET Core Event Implementation

Event callback implementation:

public void handleProgressInfo(string name, string value)
	{
	    // application code goes here.
	}

To add an event handler:

Chilkat.Dns dns = new Chilkat.Dns();
// ...
Chilkat.Dns.ProgressInfo progressInfo = new Chilkat.Dns.ProgressInfo(handleProgressInfo);
dns.setProgressInfoCb(progressInfo);
top
TaskCompleted
public event TaskCompletedEventHandler OnTaskCompleted;

Called in the background thread when an asynchronous task completes.

Chilkat .NET Event Implementation

Args are passed using Chilkat.TaskCompletedEventArgs

Event callback implementation:

private void dns_OnTaskCompleted(object sender, Chilkat.TaskCompletedEventArgs args)
	{
	    // application code goes here.
	}

To add an event handler:

Chilkat.Dns dns = new Chilkat.Dns();
dns.OnTaskCompleted += dns_OnTaskCompleted;

Chilkat Mono/.NET Core Event Implementation

Event callback implementation:

public void handleTaskIdCompleted(int taskId)
	{
	    // application code goes here.
	}

To add an event handler:

Chilkat.Dns dns = new Chilkat.Dns();
// ...
Chilkat.Dns.TaskIdCompleted taskIdCompleted = new Chilkat.Dns.TaskIdCompleted(handleTaskIdCompleted);
dns.setTaskIdCompletedCb(taskIdCompleted);
top