--- product: Chilkat product_version: 11.7.0 language: dataflex language_label: DataFlex class: Dns license: bundle deprecated: false reference_html: https://www.chilkatsoft.com/refdoc/dataflexDnsRef.html --- # Chilkat Dns — DataFlex — v11.7.0 > Chilkat 11.7.0 · language=dataflex · class=Dns > Other versions: replace `11.7.0` in this URL. Other languages: `https://www.chilkatsoft.com/ai-docs/v/11.7.0//classes/Dns.md`. > Language-wide rules (install, unlock, error model, strings/bytes): `https://www.chilkatsoft.com/ai-docs/v/11.7.0/dataflex/guide.md`. ## Purpose **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** Query common DNS record types and receive structured JSON results that are easy to inspect or pass to other application logic. **Nameserver control** Configure the nameservers Chilkat uses instead of relying only on the operating system's default DNS configuration. **DNS-over-TLS preference** Prefer DNS-over-TLS when appropriate for applications that need encrypted DNS lookups. **Timeout settings** Control how long DNS queries may wait before failing, which is useful for responsive applications and troubleshooting. **Application-wide behavior** Nameserver settings affect DNS resolution across Chilkat classes, not only the current `Dns` object. **Diagnostics** Use `LastErrorText` to troubleshoot DNS configuration, lookup failures, timeout problems, or nameserver connectivity issues. **Common pattern:** Use `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. For an extended overview, see [Dns Class Overview](https://www.chilkatsoft.com/dns_class_overview.asp). ## Object creation, unlocking and error handling **Object Creation** ```dataflex // (Dataflex programs use the 32-bit Chilkat ActiveX) Handle hoDns Get Create(RefClass(cComChilkatDns)) to hoDns ``` Call `Global.UnlockBundle` once at the start of the program, before using this or any other Chilkat class. Any string unlocks a fully functional 30-day trial; a purchased unlock code is used in production. See `guide.md` for the exact code in DataFlex. How failure is reported depends on the method's return type and is stated in the note under each method below. In every case the diagnostic text is in the `LastErrorText` property of the object whose method was called. ## Members common to every Chilkat class Documented once per language in `common-members.md`; listed here so this page is self-contained. | Property | Signature | Access | Meaning | |---|---|---|---| | `DebugLogFilePath` | `Function ComDebugLogFilePath Returns String Procedure Set ComDebugLogFilePath String value` | read/write | If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. | | `LastBinaryResult` | `Function ComLastBinaryResult Returns Variant` | read-only | This property is mainly used in SQL Server stored procedures to retrieve binary data from the last method call that returned binary data. | | `LastErrorHtml` | `Function ComLastErrorHtml Returns String` | read-only | Provides HTML-formatted information about the last called method or property. | | `LastErrorText` | `Function ComLastErrorText Returns String` | read-only | Provides plain text information about the last called method or property. | | `LastErrorXml` | `Function ComLastErrorXml Returns String` | read-only | Provides XML-formatted information about the last called method or property. | | `LastMethodSuccess` | `Function ComLastMethodSuccess Returns Boolean Procedure Set ComLastMethodSuccess Boolean value` | read/write | Indicates the success or failure of the most recent method call: `True` means success, `False` means failure. | | `LastStringResult` | `Function ComLastStringResult Returns String` | read-only | In SQL Server stored procedures, this property holds the string return value of the most recent method call that returns a string. | | `LastStringResultLen` | `Function ComLastStringResultLen Returns Integer` | read-only | The length, in characters, of the string contained in the LastStringResult property. | | `VerboseLogging` | `Function ComVerboseLogging Returns Boolean Procedure Set ComVerboseLogging Boolean value` | read/write | If set to `True`, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. | | `Version` | `Function ComVersion Returns String` | read-only | Version of the component/library, such as "10.1.0" | ## Member index | Member | Kind | Signature | |---|---|---| | `MaxWaitMs` | property, read/write | `Function ComMaxWaitMs Returns Integer Procedure Set ComMaxWaitMs Integer value` | | `NumNameservers` | property, read-only | `Function ComNumNameservers Returns Integer` | | `TlsPref` | property, read/write | `Function ComTlsPref Returns Integer Procedure Set ComTlsPref Integer value` | | `UncommonOptions` | property, read/write | `Function ComUncommonOptions Returns String Procedure Set ComUncommonOptions String value` | | `AddDefaultNameservers` | method | `Procedure ComAddDefaultNameservers` | | `AddNameserver` | method | `Procedure ComAddNameserver String ipAddr Boolean supportsTls` | | `GetNameserver` | method | `Function ComGetNameserver Integer index Returns String` | | `Query` | method | `Function ComQuery String recordType String domain cComChilkatJsonObject answer Returns Boolean` | | `RemoveAllNameservers` | method | `Procedure ComRemoveAllNameservers` | | `RemoveNameserver` | method | `Procedure ComRemoveNameserver String ipAddr` | ## Properties ### Dns.MaxWaitMs `Chilkat 11.7.0 · dataflex · Dns · MaxWaitMs · property · read/write · since 9.5.0.96` ```dataflex Function ComMaxWaitMs Returns Integer Procedure Set ComMaxWaitMs Integer value ``` 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. ### Dns.NumNameservers `Chilkat 11.7.0 · dataflex · Dns · NumNameservers · property · read-only · since 9.5.0.96` ```dataflex Function ComNumNameservers Returns Integer ``` The number of nameservers currently being used by Chilkat for DNS queries in all objects/classes, such as for HTTP, Email, FTP, SSH, etc. ### Dns.TlsPref `Chilkat 11.7.0 · dataflex · Dns · TlsPref · property · read/write · since 9.5.0.96` ```dataflex Function ComTlsPref Returns Integer Procedure Set ComTlsPref Integer value ``` 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`. ### Dns.UncommonOptions `Chilkat 11.7.0 · dataflex · Dns · UncommonOptions · property · read/write · since 11.4.0` ```dataflex Function ComUncommonOptions Returns String Procedure Set ComUncommonOptions String value ``` This is a catch-all property to be used for uncommon needs. This property defaults to the empty string and should typically remain empty. ## Methods ### Dns.AddDefaultNameservers `Chilkat 11.7.0 · dataflex · Dns · AddDefaultNameservers · method · since 9.5.0.96` ```dataflex Procedure ComAddDefaultNameservers ``` Adds the default (auto-assigned) nameservers to the collection of nameservers used by Chilkat for DNS queries and domain to IP address lookups. ### Dns.AddNameserver `Chilkat 11.7.0 · dataflex · Dns · AddNameserver · method · since 9.5.0.96` ```dataflex Procedure ComAddNameserver String ipAddr Boolean supportsTls ``` 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. ### Dns.GetNameserver `Chilkat 11.7.0 · dataflex · Dns · GetNameserver · method · since 9.5.0.96` ```dataflex Function ComGetNameserver Integer index Returns String ``` 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 ### Dns.Query `Chilkat 11.7.0 · dataflex · Dns · Query · method · since 9.5.0.96` ```dataflex Function ComQuery String recordType String domain cComChilkatJsonObject answer Returns Boolean ``` 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. Async variant: `QueryAsync` — same arguments, returns a `Task` (see Async variants below). ### Dns.RemoveAllNameservers `Chilkat 11.7.0 · dataflex · Dns · RemoveAllNameservers · method · since 9.5.0.96` ```dataflex Procedure ComRemoveAllNameservers ``` 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. ### Dns.RemoveNameserver `Chilkat 11.7.0 · dataflex · Dns · RemoveNameserver · method · since 9.5.0.96` ```dataflex Procedure ComRemoveNameserver String ipAddr ``` Removes a nameserver from the collection of nameservers used by Chilkat. The `ipAddr` is the IPv4 address of the nameserver to be removed. ## Events and callbacks This binding has no event callbacks. For progress, percent-done or cancellation use the `*Async` variant of a method and poll the returned `Task` (`PercentDone`, `Finished`, `Cancel`). ## Async variants Each returns a `Task` instead of the result and takes the same arguments as the synchronous method; run the task, wait for `Finished`, then read the result from the task. No new Async methods are added from 11.7.0 on. ```dataflex Function ComQueryAsync String recordType String domain cComChilkatJsonObject answer Returns cComChilkatTask ``` ## Related classes [`JsonObject`](https://www.chilkatsoft.com/ai-docs/v/11.7.0/dataflex/classes/JsonObject.md)