Dns PowerBuilder Reference Documentation
Dns
Current Version: 11.6.0
Chilkat.Dns
Query common DNS record types and receive structured JSON results that
are easy to inspect or pass to other application logic.
Configure the nameservers Chilkat uses instead of relying only on the
operating system's default DNS configuration.
Prefer DNS-over-TLS when appropriate for applications that need encrypted
DNS lookups.
Control how long DNS queries may wait before failing, which is useful for
responsive applications and troubleshooting.
Nameserver settings affect DNS resolution across Chilkat classes, not
only the current
Use
For an extended overview, see
Dns Class Overview.
Configure DNS resolution and query DNS records directly from Chilkat.
Chilkat.Dns is a focused class for DNS configuration and DNS
record querying. It allows applications to control the nameservers used by
Chilkat, query common DNS record types into JSON, configure DNS-over-TLS
preference, set DNS query timeouts, and obtain useful diagnostics through
LastErrorText.
DNS record queries
Nameserver control
DNS-over-TLS preference
Timeout settings
Application-wide behavior
Dns object.
Diagnostics
LastErrorText to troubleshoot DNS configuration,
lookup failures, timeout problems, or nameserver connectivity issues.
Dns either to perform direct DNS lookups, or to configure
the DNS behavior used by Chilkat as a whole. Because nameserver changes can
affect DNS resolution across Chilkat classes, treat them as application-wide
configuration rather than object-local state.
Object Creation
oleobject loo_Dns
integer li_rc
loo_Dns = create oleobject
li_rc = loo_Dns.ConnectToNewObject("Chilkat.Dns")
if li_rc < 0 then
destroy loo_Dns
MessageBox("Error","Connecting to COM object failed")
return
end if
// ... use loo_Dns ...
destroy loo_DnsPowerBuilder uses the Chilkat ActiveX through an oleobject: declare the variable, create it, connect it to the Chilkat class with ConnectToNewObject, and destroy it when finished. A negative return code from ConnectToNewObject means the ActiveX is not registered, or the registered ActiveX does not match the bitness (32-bit or 64-bit) of the PowerBuilder target.
Objects returned by methods (such as an HttpResponse or JsonObject) are also oleobject variables and must likewise be destroyed. A method that fails to return an object returns null; test with IsNull(). In the signatures on this page, the Chilkat class name identifies which object is expected or returned; the PowerBuilder variable type is always oleobject.
To bind to a specific major version of Chilkat, append the major version number to the ProgID, such as ConnectToNewObject("Chilkat.Dns.11") for Chilkat v11.*.*.
Members typed blob exchange binary data as a Variant byte array. The PowerBuilder examples instead use the BinData-based alternatives (methods ending in Bd), which keep binary data inside Chilkat objects.
Properties
DebugLogFilePath
If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. This logging helps identify the context and history of Chilkat calls leading up to any crash or hang, aiding in debugging.
Enabling the VerboseLogging property provides more detailed information. This property is mainly used for debugging rare instances where a Chilkat method call causes a hang or crash, which should generally not happen.
Possible causes of hangs include:
- A timeout property set to 0, indicating an infinite timeout.
- A hang occurring within an event callback in the application code.
- An internal bug in the Chilkat code causing the hang.
LastBinaryResult
This property is mainly used in SQL Server stored procedures to retrieve binary data from the last method call that returned binary data. It is only accessible if Chilkat.Global.KeepBinaryResult is set to 1. This feature allows for the retrieval of large varbinary results in an SQL Server environment, which has restrictions on returning large data via method calls, though temp tables can handle binary properties.
LastErrorHtml
Provides HTML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
topLastErrorText
Provides plain text information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
LastErrorXml
Provides XML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
topLastMethodSuccess
Indicates the success or failure of the most recent method call: 1 means success, 0 means failure. This property remains unchanged by property setters or getters. This method is present to address challenges in checking for null or Nothing returns in certain programming languages. Note: This property does not apply to methods that return integer values or to boolean-returning methods where the boolean does not indicate success or failure.
LastStringResult
In SQL Server stored procedures, this property holds the string return value of the most recent method call that returns a string. It is accessible only when Chilkat.Global.KeepStringResult is set to TRUE. SQL Server has limitations on string lengths returned from methods and properties, but temp tables can be used to access large strings.
LastStringResultLen
The length, in characters, of the string contained in the LastStringResult property.
topMaxWaitMs
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.
topNumNameservers
The number of nameservers currently being used by Chilkat for DNS queries in all objects/classes, such as for HTTP, Email, FTP, SSH, etc.
topTlsPref
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 1.
UncommonOptions
This is a catch-all property to be used for uncommon needs. This property defaults to the empty string and should typically remain empty.
topVerboseLogging
If set to 1, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is 0. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.
Version
Methods
AddDefaultNameservers
Adds the default (auto-assigned) nameservers to the collection of nameservers used by Chilkat for DNS queries and domain to IP address lookups.
AddNameserver
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.
GetNameserver
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
Query
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.
QueryAsync (1)
Creates an asynchronous task to call the Query method with the arguments provided.
Returns null on failure
RemoveAllNameservers
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.
RemoveNameserver
Removes a nameserver from the collection of nameservers used by Chilkat. The ipAddr is the IPv4 address of the nameserver to be removed.