MX Record Senor not working on PRTG Server

Are you using a custom sensor, or the DNS sensor included with PRTG? That error is related to EXE sensors.

Hi Benjamin

Thanks for the reply. I'm using the custom DNS sensor on the local probe (which is an Azure VM W2016 Server)

Thanks TG

I can't say I'm familiar with a custom DNS sensor. Is this a custom script sensor?

Hi Benjamin

Sorry I didn't mean to type the word custom - its just a normal DNS sensor with MX Record option ticked?

Thanks TG

Does the PRTG server have an MX record in your DNS?

This sensor takes the IP of the host, and does an DNS query on it. So you're asking for DNS to return the MX record for your PRTG server.

No the PRTG server does not have an MX Record - I wanted to use it to look up other public MX records for clients of ours.

I got the MX record sensor working on a remote probe server which doesn't have any MX records on it either nor does it host any. The only difference between the PRTG server and the remote server is that the remote server is my domain controller and is also a local DNS server for my lan.

I don't know why the PRTG server wont use its own public DNS to resolve the MX records of our clients domains?

If the server the DNS sensor is on, does not have the record type that you are polling for, it will return an error.

The DNS sensor is used to verify that the correct DNS record is being returned for the target host.

So if you put a DNS sensor asking for the A Name of a server, the sensor will return OK and the IP address it received from DNS with the A Name.

If you ask for the MX record, and there is none, it will return an error.

What was the returned value for the MX record of that Remote Probe?

Thanks - I think you might be getting confused and me as well :-)

I have a remote probe - PRTG will also be to create a DNS Sensor and select MX record option - it then asks me what domain would I like to look up the MX record for e.g. microsoft.com and then the sensor asks me to populate what it should return.

When I save the sensor (on the remote probe device - which also is a domain controller and DNS server) it will go and check the MX record of microsoft.com and check it against the value in the sensor and let me know if it passes (green) or fails (red).

When I create this exact same sensor on the PRTG core server (which is not a domain controller or DNS server) the sensor returns nothing. Even though on the PRTG core server can resolve DNS queries (as I can run a command in the command line to get the correct MX record for microsoft.com)

I'm wondering why the sensor works on the remote probe and not on my local PRTG core server?

Ok, let's have you turn on the option in Settings to Write the Result to Disk.

The result file is located in %programdata%/Paessler/PRTG Network Monitor/Logs(Sensors)

Let me know what the file indicates.