The DNS v2 sensor monitors a Domain Name System (DNS) server, resolves domain name records, and compares them to a filter.

i_round_blueThe sensor can show the Down status if the DNS server does not correctly resolve a specified domain name

DNS v2 Sensor

DNS v2 Sensor

i_square_cyanFor a detailed list and descriptions of the channels that this sensor can show, see section Channel List.

Sensor in Other Languages

  • Dutch: DNS v2
  • French: DNS v2
  • German: DNS v2
  • Japanese: DNS v2
  • Portuguese: DNS v2
  • Russian: DNS v2
  • Simplified Chinese: DNS v2
  • Spanish: DNS v2


  • This sensor supports the IPv6 protocol.
  • This sensor has a medium performance impact.
  • This sensor uses lookups to determine the status values of one or more channels. This means that possible states are defined in a lookup file. You can change the behavior of a channel by editing the lookup file that the channel uses. For details, see section Define Lookups.

Add Sensor

The Add Sensor dialog appears when you manually add a new sensor to a device. It only shows the settings that are required to create the sensor. You can change nearly all settings on the sensor's Settings tab after creation.

Basic Sensor Settings

Click the Settings tab of a sensor to change its settings.

Basic Sensor Settings

Basic Sensor Settings



Sensor Name

Enter a name to identify the sensor.

Parent Tags

Shows tags that the sensor inherits from its parent device, parent group, and parent probe.

i_round_blueThis setting is for your information only. You cannot change it.


Enter one or more tags. Confirm each tag with the Spacebar key, a comma, or the Enter key. You can use tags to group objects and use tag-filtered views later on. Tags are not case-sensitive. Tags are automatically inherited.

i_round_blueIt is not possible to enter tags with a leading plus (+) or minus (-) sign, nor tags with parentheses (()) or angle brackets (<>).

i_round_blueFor performance reasons, it can take some minutes until you can filter for new tags that you added.

The sensor has the following default tags that are automatically predefined in the sensor's settings when you add the sensor:

  • dns
  • dnssensor


Select a priority for the sensor. This setting determines the position of the sensor in lists. The highest priority is at the top of a list. Choose from the lowest priority (i_priority_1) to the highest priority (i_priority_5).

i_round_blueUsually, a sensor connects to the IP Address/DNS Name of the parent device. See the device settings for details. For some sensors, you can explicitly define the monitoring target in the sensor settings.

DNS Sensor Specific

DNS Sensor Specific

DNS Sensor Specific



Domain Name

Enter the DNS name to resolve.

i_round_blueIf you use the query type PTR resource record (PTR), enter a proper reverse DNS representation of the IP address. For example,

Query Type

Select the query type that the sensor sends to the DNS server:

  • Host address IPv4 (A) (default)
  • Host address IPv6 (AAAA)
  • Canonical name for an alias (CNAME)
  • Mail exchange (MX)
  • Naming authority pointer (NAPTR)
  • Authoritative name server (NS)
  • PTR resource record (PTR)
  • Start of a zone of authority marker (SOA)
  • Text resource record (TXT)
  • Any (depends on the DNS server configuration)

Timeout (Sec.)

Enter a timeout in seconds for the request. Enter an integer. The maximum timeout value is 900 seconds (15 minutes).

i_round_blueIf the reply takes longer than this value, the sensor cancels the request and shows a corresponding error message.

i_round_redThe timeout value must be shorter than the scanning interval of the sensor.

Filter Usage

Define if the sensor checks for a specific filter value in the response.

  • Do not use a filter (default): Do not check the response.
  • Use a filter: Use a filter to check the response. Define the filter value below.

Filter Value

This setting is only visible if you select Filter Usage above. Enter one or more filter values. For an A record, the filter value can be an IP address like, for example. The filter value can also contain a wildcard (*) to match any content, for example 127.*.1. You can specify multiple filter values by using a comma as separator, for example 172.217.*.1,172.217.*.2.


Enter the number of the port to which the sensor tries to connect. This must be the port on which the parent device answers queries. The default port is 53.

i_round_blueWe recommend that you use the default value.

i_round_blueThe sensor connects to the IP address or the DNS name of the parent device.

Sensor Display

Sensor Display

Sensor Display



Primary Channel

Select a channel from the list to define it as the primary channel. In the device tree, the last value of the primary channel is always displayed below the sensor's name. The available options depend on what channels are available for this sensor.

i_round_blueYou can set a different primary channel later by clicking b_channel_primary below a channel gauge on the sensor's Overview tab.

Graph Type

Define how different channels are shown for this sensor:

  • Show channels independently (default): Show a graph for each channel.
  • Stack channels on top of each other: Stack channels on top of each other to create a multi-channel graph. This generates a graph that visualizes the different components of your total traffic.
    i_round_redYou cannot use this option in combination with manual Vertical Axis Scaling (available in the channel settings).

Stack Unit

This setting is only visible if you enable Stack channels on top of each other as Graph Type. Select a unit from the list. All channels with this unit are stacked on top of each other. By default, you cannot exclude single channels from stacking if they use the selected unit. However, there is an advanced procedure to do so.

Debug Options

Debug Options

Debug Options



Result Handling

Define what PRTG does with the sensor result:

  • Discard result: Do not store the sensor result.
  • Store result: Store the last sensor result in the \Logs\sensors subfolder of the PRTG data directory on the probe system. The file name is Result of Sensor [ID].log. This setting is for debugging purposes. PRTG overwrites this file with each scanning interval.

i_podThis option is not available when the sensor runs on the hosted probe of a PRTG Hosted Monitor instance.

i_round_blueIn a cluster, PRTG stores the result in the PRTG data directory of the master node.

Inherited Settings

By default, all of these settings are inherited from objects that are higher in the hierarchy. We recommend that you change them centrally in the root group settings if necessary. To change a setting for this object only, click b_inherited_enabled under the corresponding setting name to disable the inheritance and to display its options.

i_square_cyanFor more information, see section Inheritance of Settings.

Scanning Interval

Scanning Interval

Scanning Interval

i_square_cyanFor more information, see section Root Group Settings, section Scanning Interval.

Schedules, Dependencies, and Maintenance Window

i_round_blueYou cannot interrupt the inheritance for schedules, dependencies, and maintenance windows. The corresponding settings from the parent objects are always active. However, you can define additional schedules, dependencies, and maintenance windows. They are active at the same time as the parent objects' settings.

Schedules, Dependencies, and Maintenance Window

Schedules, Dependencies, and Maintenance Window

i_square_cyanFor more information, see section Root Group Settings, section Schedules, Dependencies, and Maintenance Window.

Access Rights

Access Rights

Access Rights

i_square_cyanFor more information, see section Root Group Settings, section Access Rights.

Channel Unit Configuration

i_round_blueWhich channel units are available depends on the sensor type and the available parameters. If no configurable channels are available, this field shows No configurable channels.

Channel Unit Configuration

Channel Unit Configuration

i_square_cyanFor more information, see section Root Group Settings, section Channel Unit Configuration.

Channel List

i_round_blueWhich channels the sensor actually shows might depend on the target device, the available components, and the sensor setup.




In the channel table on the Overview tab, this channel never shows any values. PRTG uses this channel in graphs and reports to show the amount of time in which the sensor was in the Down status in percent.

Matched Record Count

The number of matched records (if you use a filter)

Record Count

The number of records

Records Resolved

If records were resolved

  • Up status: Yes
  • Down status: No

Response Time

The response time in msec

i_round_blueThis channel is the primary channel by default.


i_square_blueKnowledge Base

What security features does PRTG include?