PRTG Manual: DNS v2 Sensor

Sensor Name

Enter a name to identify the sensor. By default, PRTG shows this name in the device tree, as well as in alarms, logs, notifications, reports, maps, libraries, and tickets.

If the name contains angle brackets (<>), PRTG replaces them with braces ({}) for security reasons. For more information, see the Knowledge Base: What security features does PRTG include?

Parent Tags

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

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

Tags

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.

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

For 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

Priority

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 () to the highest priority ().

Domain Name

Enter the DNS name to resolve.

If you use the query type PTR resource record (PTR), enter a proper reverse DNS representation of the IP address. For example, 1.0.0.127.in-addr.arpa.

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).

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

The 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 127.0.0.1, 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.

Port

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.

We recommend that you use the default value.

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

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.

You can set a different primary channel later by clicking 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.
  You 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.

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.

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

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

Downtime

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

This channel is the primary channel by default.