---
title: DNS Testing
description: Monitor resolvability and lookup times of your DNS records
breadcrumbs: Docs > Synthetic Testing and Monitoring > API Testing > DNS Testing
---

# DNS Testing

## Overview{% #overview %}

DNS tests allow you to proactively monitor the resolvability and lookup times of your DNS records using any nameserver. If resolution is unexpectedly slow or a DNS server answers with unexpected A, AAAA, CNAME, TXT, or MX entries, Datadog sends you an alert with details on the failure, allowing you to quickly pinpoint the root cause of the issue and fix it.

DNS tests can run from both managed and [private locations](https://docs.datadoghq.com/synthetics/private_locations.md) depending on your preference for running the test from outside or inside your network. DNS tests can run on a schedule, on-demand, or directly within your [CI/CD pipelines](https://docs.datadoghq.com/synthetics/cicd_integrations.md).

## Configuration{% #configuration %}

You may create a test using one of the following options:

- **Create a test from a template**:

  1. Hover over one of the pre-populated templates and click **View Template**. This opens a side panel displaying pre-populated configuration information, including: Test Details, Request Details, Assertions, Alert Conditions, and Monitor Settings.

  1. Click **+Create Test** to open the **Define Request** page, where you can review and edit the pre-populated configuration options. The fields presented are identical to those available when creating a test from scratch.

  1. Click **Save Details** to submit your API test.

     {% video
        url="https://docs.dd-static.net/images/getting_started/synthetics/synthetics_templates_api_video.mp4" /%}

- **Build a test from scratch**:

  1. To build a test from scratch, click the **+ Start from scratch** template, then select the DNS request type.
  1. Specify the **Domain** you want your test to query. For example, `www.example.com`.
  1. Specify the **DNS Server** to use (optional), it can be a domain name or an IP address. If not specified, your DNS test performs resolution using `8.8.8.8`, with a fallback on `1.1.1.1` and an internal AWS DNS server.
  1. Specify your DNS Server **Port** (optional). If not specified, the DNS Server port defaults to 53.
  1. Specify the amount of time in seconds before the test times out (optional).
  1. **Name** your DNS test.
  1. Add Environment **Tags** as well as any other tag to your DNS test. You can then use these tags to filter through your Synthetic tests on the [Synthetic Monitoring & Continuous Testing page](https://docs.datadoghq.com/synthetics/search.md#search).
  1. Click **Test Domain** to try out the request configuration. A response preview is displayed on the right side of your screen.

  {% image
     source="https://docs.dd-static.net/images/synthetics/api_tests/synthetics_dns_test_domain.fd9b11b1c90a7f48c046683f0f3cce6d.png?auto=format&fit=max&w=850 1x, https://docs.dd-static.net/images/synthetics/api_tests/synthetics_dns_test_domain.fd9b11b1c90a7f48c046683f0f3cce6d.png?auto=format&fit=max&w=850&dpr=2 2x"
     alt="Define DNS query" /%}

  1. Click **Create Test** to submit your API test.

### Snippets{% #snippets %}

When setting up a new Synthetic Monitoring API test, use snippets to automatically fill in basic auth, performance, and regions, rather than selecting these options manually. The following snippets are available:

- **Basic Auth**: Automatically test your APIs using pre-populated basic auth headers, JavaScript, bearer token, and API/app key auth variables.

- **Performance**: Automatically configure a test with the shortest frequency (one minute), perform a gRPC health check, and test for overall response time latency with a breakdown of network timing.

- **Regions**: Automatically test your API endpoint against a location in each of the three primary geographic regions (AMER, APAC and EMEA).

### Define assertions{% #define-assertions %}

Assertions define what an expected test result is. After you click **Test URL**, basic assertions on `response time` and available records are added. You must define at least one assertion for your test to monitor.

| Type                   | Record type                                                                 | Operator                                     | Value type                                                                                           |
| ---------------------- | --------------------------------------------------------------------------- | -------------------------------------------- | ---------------------------------------------------------------------------------------------------- |
| response time          | `is less than`                                                              | *Integer (ms)*                               |
| every available record | of type A, of type AAAA, of type CNAME, of type MX, of type NS, of type TXT | `is`, `contains`,`matches`, `does not match` | *String**[Regex](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions)* |
| at least one record    | of type A, of type AAAA, of type CNAME, of type MX, of type NS, of type TXT | `is`, `contains`,`matches`, `does not match` | *String**[Regex](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions)* |

**Note**: SOA records are not available for testing using Synthetic tests.

You can create up to 20 assertions per API test by clicking **New Assertion** or by clicking directly on the response preview:

{% image
   source="https://docs.dd-static.net/images/synthetics/api_tests/assertions_dns.99d791766ec174a706b275ab0b928deb.png?auto=format&fit=max&w=850 1x, https://docs.dd-static.net/images/synthetics/api_tests/assertions_dns.99d791766ec174a706b275ab0b928deb.png?auto=format&fit=max&w=850&dpr=2 2x"
   alt="Define assertions for your DNS test to succeed or fail on" /%}

To perform `OR` logic in an assertion, use the `matches regex` comparator to define a regex with multiple expected values for the same assertion type like `(0|100)`. The test result is successful if every available record or at least one record assertions' value is 0 or 100.

If a test does not contain an assertion on the response body, the body payload drops and returns an associated response time for the request within the timeout limit set by the Synthetics Worker.

If a test contains an assertion on the response body and the timeout limit is reached, an `Assertions on the body/response cannot be run beyond this limit` error appears.

### Select locations{% #select-locations %}

Select the **Locations** to run your DNS test from. DNS tests can run from both managed and [private locations](https://docs.datadoghq.com/synthetics/private_locations.md) depending on your preference for monitoring a public or private domain.

Datadog's out-of-the-box managed locations allow you to test public-facing websites and endpoints from regions where your customers are located.

**AWS**:

| Americas            | Asia Pacific | EMEA      |
| ------------------- | ------------ | --------- |
| Canada Central      | Hong Kong    | Bahrain   |
| Northern California | Jakarta      | Cape Town |
| Northern Virginia   | Mumbai       | Frankfurt |
| Ohio                | Osaka        | Ireland   |
| Oregon              | Seoul        | London    |
| São Paulo           | Singapore    | Milan     |
| Sydney              | Paris        |
| Tokyo               | Stockholm    |

**GCP**:

| Americas    | Asia Pacific | EMEA      |
| ----------- | ------------ | --------- |
| Dallas      | Tokyo        | Frankfurt |
| Los Angeles |
| Oregon      |
| Virginia    |

**Azure**:

| Region   | Location |
| -------- | -------- |
| Americas | Virginia |

The Datadog for Government site (US1-FED) uses the following managed location:

| Region   | Location |
| -------- | -------- |
| Americas | US-West  |

### Specify test frequency{% #specify-test-frequency %}

DNS tests can run:

- **On a schedule** to ensure your most important services are always accessible to your users. Select the frequency at which you want Datadog to run your DNS test.
- [**Within your CI/CD pipelines**](https://docs.datadoghq.com/synthetics/cicd_integrations.md).
- **On-demand** to run your tests whenever makes the most sense for your team.

### Define alert conditions{% #define-alert-conditions %}

Set alert conditions to determine the circumstances under which you want a test to fail and trigger an alert.

#### Alerting rule{% #alerting-rule %}

When you set the alert conditions to: `An alert is triggered if any assertion fails for X minutes from any n of N locations`, an alert is triggered only if these two conditions are true:

- At least one location was in failure (at least one assertion failed) during the last *X* minutes;
- At one moment during the last *X* minutes, at least *n* locations were in failure.

#### Fast retry{% #fast-retry %}

Your test can trigger retries `X` times after `Y` ms in case of a failed test result. Customize the retry interval to suit your alerting sensibility.

Location uptime is computed on a per-evaluation basis (whether the last test result before evaluation was up or down). The total uptime is computed based on the configured alert conditions. Notifications sent are based on the total uptime.

{% alert level="info" %}
For more information on how Synthetic Monitoring notifications evaluate test results and trigger alerts, see [Understanding Synthetic Monitor Alerting](https://docs.datadoghq.com/synthetics/guide/how-synthetics-monitors-trigger-alerts.md).
{% /alert %}

### Configure the test monitor{% #configure-the-test-monitor %}

A notification is sent by your test based on the alerting conditions previously defined. Use this section to define how and what to message your team.

1. [Similar to how you configure monitors](https://docs.datadoghq.com/monitors/notify.md?tab=is_alert#configure-notifications-and-automations), select **users and/or services** that should receive notifications either by adding an `@notification` to the message or by searching for team members and connected integrations with the dropdown menu.

1. Enter the notification **message** for your test or use pre-filled monitor messages. This field allows standard [Markdown formatting](http://daringfireball.net/projects/markdown/syntax) and supports the following [conditional variables](https://docs.datadoghq.com/monitors/notify/variables.md?tab=is_alert#conditional-variables):

| Conditional Variable | Description                                          |
| -------------------- | ---------------------------------------------------- |
| `{{#is_alert}}`      | Show when the test alerts.                           |
| `{{^is_alert}}`      | Show unless the test alerts.                         |
| `{{#is_recovery}}`   | Show when the test recovers from alert.              |
| `{{^is_recovery}}`   | Show unless the test recovers from alert.            |
| `{{#is_renotify}}`   | Show when the monitor renotifies.                    |
| `{{^is_renotify}}`   | Show unless the monitor renotifies.                  |
| `{{#is_priority}}`   | Show when the monitor matches priority (P1 to P5).   |
| `{{^is_priority}}`   | Show unless the monitor matches priority (P1 to P5). |

Notification messages include the **message** defined in this section and information about the failing locations. Pre-filled monitor messages are included in the message body section:

Specify how often you want your test to **re-send the notification message** in case of test failure. To prevent renotification on failing tests, check the option `Stop re-notifying on X occurrences`.

Click **Save & Start Recording** to save your test configuration and monitor.

For more information, see [Synthetic Monitoring notifications](https://docs.datadoghq.com/synthetics/notifications.md).

### Downtimes{% #downtimes %}

To pause test execution during planned maintenance windows, select an existing [Scheduled downtime](https://docs.datadoghq.com/synthetics/platform/downtime.md) in the **Downtimes** section. The test automatically pauses during the downtime's scheduled time slots.

**Note**: You cannot create a new downtime from the test creation form. To create one, navigate to [**Settings > Downtimes**](https://app.datadoghq.com/synthetics/settings/downtimes).

### Create local variables{% #create-local-variables %}

To create a local variable, click **+ All steps > Variables**. You can select one of the following available builtins to add to your variable string:

{% dl %}

{% dt %}
{{ numeric(n) }}
{% /dt %}

{% dd %}
Generates a numeric string with `n` digits.
{% /dd %}

{% dt %}
{{ alphabetic(n) }}
{% /dt %}

{% dd %}
Generates an alphabetic string with `n` letters.
{% /dd %}

{% dt %}
{{ alphanumeric(n) }}
{% /dt %}

{% dd %}
Generates an alphanumeric string with `n` characters.
{% /dd %}

{% dt %}
{{ date(n unit, format) }}
{% /dt %}

{% dd %}
Generates a date in one of Datadog's accepted formats with a value corresponding to the UTC date the test is initiated at + or - `n` units.
{% /dd %}

{% dt %}
{{ timestamp(n, unit) }}
{% /dt %}

{% dd %}
Generates a timestamp in one of Datadog's accepted units with a value corresponding to the UTC timestamp the test is initiated at +/- `n` units.
{% /dd %}

{% dt %}
{{ uuid }}
{% /dt %}

{% dd %}
Generates a version 4 universally unique identifier (UUID).
{% /dd %}

{% dt %}
{{ public-id }}
{% /dt %}

{% dd %}
Injects the Public ID of your test.
{% /dd %}

{% dt %}
{{ result-id }}
{% /dt %}

{% dd %}
Injects the Result ID of your test run.
{% /dd %}

{% /dl %}

To obfuscate local variable values in test results, select **Hide and obfuscate variable value**. Once you have defined the variable string, click **Add Variable**.

### Use variables{% #use-variables %}

You can use the [global variables defined on the **Settings** page](https://docs.datadoghq.com/synthetics/settings.md#global-variables) in the URL, advanced options, and assertions of your DNS tests.

To display your list of variables, type `{{` in your desired field.

## Test failure{% #test-failure %}

A test is considered `FAILED` if it does not satisfy one or more assertions or if the request prematurely failed. In some cases, the test can fail without testing the assertions against the endpoint.

For a complete list of DNS error codes, see [API Testing Errors](https://docs.datadoghq.com/synthetics/api_tests/errors.md).

## Permissions{% #permissions %}

By default, only users with the [Datadog Admin and Datadog Standard roles](https://docs.datadoghq.com/account_management/rbac.md) can create, edit, and delete Synthetic DNS tests. To get create, edit, and delete access to Synthetic DNS tests, upgrade your user to one of those two [default roles](https://docs.datadoghq.com/account_management/rbac.md).

If you are using the [custom role feature](https://docs.datadoghq.com/account_management/rbac.md#custom-roles), add your user to any custom role that includes `synthetics_read` and `synthetics_write` permissions.

### Restrict access{% #restrict-access %}

Use [granular access control](https://docs.datadoghq.com/account_management/rbac/granular_access.md) to limit who has access to your test based on roles, teams, or individual users:

1. Open the permissions section of the form.
1. Click **Edit Access**.
Click **Restrict Access**.Select teams, roles, or users.Click **Add**.Select the level of access you want to associate with each of them.Click **Done**.
{% alert level="info" %}
You can view results from a Private Location even without Viewer access to that Private Location.
{% /alert %}

| Access level | View test configuration | Edit test configuration | View test results | Run test |
| ------------ | ----------------------- | ----------------------- | ----------------- | -------- |
| No access    |
| Viewer       | Yes                     | Yes                     |
| Editor       | Yes                     | Yes                     | Yes               | Yes      |

## Further Reading{% #further-reading %}

- [Introducing Datadog Synthetic Monitoring](https://www.datadoghq.com/blog/introducing-synthetic-monitoring/)
- [DNS monitoring with Datadog](https://www.datadoghq.com/blog/monitor-dns-with-datadog/)
- [Get started with API tests](https://docs.datadoghq.com/getting_started/synthetics/api_test.md)
- [Test DNS resolution of your internal endpoints](https://docs.datadoghq.com/synthetics/private_locations.md)
- [Learn about Synthetic test monitors](https://docs.datadoghq.com/synthetics/guide/synthetic-test-monitors.md)