---
product: Chilkat
product_version: 11.7.0
language: phpx
language_label: PHP ActiveX
class: Dns
license: bundle
deprecated: false
reference_html: https://www.chilkatsoft.com/refdoc/phpDnsRef.html
---
# Chilkat Dns — PHP ActiveX — v11.7.0

> Chilkat 11.7.0 · language=phpx · class=Dns
> Other versions: replace `11.7.0` in this URL. Other languages: `https://www.chilkatsoft.com/ai-docs/v/11.7.0/<lang>/classes/Dns.md`.
> Language-wide rules (install, unlock, error model, strings/bytes): `https://www.chilkatsoft.com/ai-docs/v/11.7.0/phpx/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**

```php
Chilkat v10.0.0 or greater:
$obj = new COM("Chilkat.Dns");
Chilkat v9.5.0.*:
$obj = new COM("Chilkat_9_5_0.Dns");
```

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 PHP ActiveX.

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` | `string DebugLogFilePath` | 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` | `VARIANT LastBinaryResult (read-only)` | 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` | `string LastErrorHtml (read-only)` | read-only | Provides HTML-formatted information about the last called method or property. |
| `LastErrorText` | `string LastErrorText (read-only)` | read-only | Provides plain text information about the last called method or property. |
| `LastErrorXml` | `string LastErrorXml (read-only)` | read-only | Provides XML-formatted information about the last called method or property. |
| `LastMethodSuccess` | `bool LastMethodSuccess` | read/write | Indicates the success or failure of the most recent method call: `true` means success, `false` means failure. |
| `LastStringResult` | `string LastStringResult (read-only)` | 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` | `int LastStringResultLen (read-only)` | read-only | The length, in characters, of the string contained in the LastStringResult property. |
| `VerboseLogging` | `bool VerboseLogging` | read/write | If set to `true`, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. |
| `Version` | `string Version (read-only)` | read-only | Version of the component/library, such as "10.1.0" |

## Member index

| Member | Kind | Signature |
|---|---|---|
| `MaxWaitMs` | property, read/write | `int MaxWaitMs` |
| `NumNameservers` | property, read-only | `int NumNameservers (read-only)` |
| `TlsPref` | property, read/write | `int TlsPref` |
| `UncommonOptions` | property, read/write | `string UncommonOptions` |
| `AddDefaultNameservers` | method | `void AddDefaultNameservers()` |
| `AddNameserver` | method | `void AddNameserver(string ipAddr, bool supportsTls)` |
| `GetNameserver` | method | `string GetNameserver(int index)` |
| `Query` | method | `bool Query(string recordType, string domain, Chilkat.JsonObject answer)` |
| `RemoveAllNameservers` | method | `void RemoveAllNameservers()` |
| `RemoveNameserver` | method | `void RemoveNameserver(string ipAddr)` |

## Properties

### Dns.MaxWaitMs

`Chilkat 11.7.0 · phpx · Dns · MaxWaitMs · property · read/write · since 9.5.0.96`

```php
int MaxWaitMs
```

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 · phpx · Dns · NumNameservers · property · read-only · since 9.5.0.96`

```php
int NumNameservers (read-only)
```

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 · phpx · Dns · TlsPref · property · read/write · since 9.5.0.96`

```php
int TlsPref
```

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 · phpx · Dns · UncommonOptions · property · read/write · since 11.4.0`

```php
string 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.

## Methods

### Dns.AddDefaultNameservers

`Chilkat 11.7.0 · phpx · Dns · AddDefaultNameservers · method · since 9.5.0.96`

```php
void AddDefaultNameservers()
```

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 · phpx · Dns · AddNameserver · method · since 9.5.0.96`

```php
void AddNameserver(string ipAddr, bool 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 · phpx · Dns · GetNameserver · method · since 9.5.0.96`

```php
string GetNameserver(int index)
```

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 · phpx · Dns · Query · method · since 9.5.0.96`

```php
bool Query(string recordType, string domain, Chilkat.JsonObject answer)
```

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 · phpx · Dns · RemoveAllNameservers · method · since 9.5.0.96`

```php
void 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.

### Dns.RemoveNameserver

`Chilkat 11.7.0 · phpx · Dns · RemoveNameserver · method · since 9.5.0.96`

```php
void RemoveNameserver(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.

```php
Chilkat.Task QueryAsync(string recordType, string domain, Chilkat.JsonObject answer)
```

## Related classes

[`JsonObject`](https://www.chilkatsoft.com/ai-docs/v/11.7.0/phpx/classes/JsonObject.md)