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Does the IP on DNS blacklist sensor use the private or public IP? And how can this be checked?



I have an IP on DNS blacklist sensor and I want to make sure it is using the private IP. Does the sensor default to private or public and how can I check this?

blacklist dns ip-address prtg

Created on Jun 15, 2020 8:38:36 PM

1 Reply



The sensor uses the IP address or DNS-hostname configured in the setting "IPv4 Address/DNS Name" in the parent device. If you configure a DNS hostname, this hostname gets resolved to an IP address before doing the check.
The resolved IP-address depends on the DNS server you are using on your PRTG host. Therefore you have to make sure, the used DNS-hostname gets resolved to the internal IP address or configure this internal address in the parent device settings.
Please take a look at the sensor documentation, at the section remarks, where this is also explained: https://www.paessler.com/manuals/prtg/ip_on_dns_blacklist_sensor

Be aware that if you want to check services on both the internal and external IP addresses of this device, you have to create two devices within PRTG and configure each with the private or public address.

You can either check the name-resolution manually on the PRTG host by doing a "nslookup $device-dns-hostname" or create a new device for your DNS-Server and add an "DNS v2" sensor (https://www.paessler.com/manuals/prtg/dns_v2_sensor) with the DNS-hostname you want to resolve. You can then use a "Filter Value" to make sure it resolves to the private IP-address.

Kind Regards,
Matthias Kupfer - Team Tech Support

Created on Jun 16, 2020 12:34:15 PM by  Matthias Kupfer [Paessler Support]

Disclaimer: The information in the Paessler Knowledge Base comes without warranty of any kind. Use at your own risk. Before applying any instructions please exercise proper system administrator housekeeping. You must make sure that a proper backup of all your data is available.