PRTG Manual: DNS v2 Sensor

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

i_round_blueThis 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


Consider the following remarks and requirements for this sensor:




  • This sensor supports IPv6.

Performance impact

  • This sensor has a medium performance impact.


  • This sensor uses lookups to determine the status values of one or more channels.

Multi-platform probe

  • You can add this sensor to a multi-platform probe.

Basic Sensor Settings

Basic Sensor Settings

Basic Sensor Settings

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

  • dns
  • dnssensor

i_square_cyanFor more information about basic sensor settings, see section 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 authority (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 Use a filter 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 this sensor connects. 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_blueThis 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, PRTG displays the last value of the primary channel 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 this sensor shows different channels:

  • 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 select Stack channels on top of each other above.

Select a unit from the list. PRTG stacks all channels with this unit 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 (default): 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.

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

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

i_round_blueThis channel is the primary channel by default.


i_square_blueKNOWLEDGE BASE

What security features does PRTG include?