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Alerting on failed DNS lookups




I would like to receive alerts on any failed DNS lookups- i.e. an endpoint in my environment attempts to connect with a domain name that could not be resolved - i.e. domain does not exist.

Is this possible with PRTG?

Thank you Tony

dns dns-lookup dns-resolution

Created on Nov 27, 2015 5:02:23 PM

4 Replies



Hi specialist,

You can use a simple ping sensor for this.
Have the parent device point at the DNS name, if it cannot be resolved, the ping will fail.

Created on Nov 30, 2015 1:16:36 PM



Thank you.

I will try this :-)

BTW - is it possible that the domain's firewall or boundary router will be configured to reject ICMP traffic - assuming ICMP ping is what you're referring to?

Created on Nov 30, 2015 1:28:51 PM



Absolutely, routers cen be setup to drop ICMP when they get too busy.

But you can also use a http sensor if you like as long as you use a DNS name.

Created on Nov 30, 2015 1:50:39 PM



Thank you again.

The goal is not ad-hoc active checks. We need to alert on DNS failures as a result of a look up by any endpoint.

We could use Wireshark to sniff traffic and apply a filter to show up DNS failure messages. these can then be investigated.

Thanks Tony

Created on Nov 30, 2015 3:19:51 PM

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.