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After I updated PRTG, my Ping and Port sensors suddenly show shorter response times. What happened?



I upgraded to PRTG version 8.2.x. Afterwards, my Ping and Port sensors show significantly lower response times. What has happened?

dns-resolution ping port prtg response-time update v82

Created on Jan 13, 2011 11:37:38 AM by  Daniel Zobel [Product Manager]

Last change on Jan 17, 2011 2:24:36 PM by  Daniel Zobel [Product Manager]

3 Replies

Accepted Answer



This article applies to PRTG Network Monitor 8.2 or later

Behavior of Ping and Port Sensor Changed

With PRTG version 8.2, we changed the way Ping and Port sensors measure response times.

The Old Method

In previous versions, PRTG always added the time needed to resolve a DNS name to an IP address to the response time measured for actual Ping and Port requests:

Result value = DNS resolution time + response time

For Ping requests, for example, this resulted in different values reported by PRTG, when compared to the results shown by the Windows Ping command, when a DNS name was pinged. However, measurements for host names containing an IP address were not affected by this issue, as DNS resolution is not required in these cases.

What's New As Of Version 8.2?

Due to frequent user requests, we now changed the default behavior of Ping and Port sensors so they now merely show the response time without the DNS resolution:

Result value = response time

In your monitoring graphs, you might therefore notice a huge drop in response times for these sensor types (depending on the performance of your DNS servers).

Can I Still Use the Old Method?

If the changed values are a problem for you, and you want to restore the old measurement method after upgrading to PRTG 8.2, there is a registry setting that allows to enable the old method.

For detailed instructions, please see: How can I change the default behavior of Ping and Port sensors regarding DNS resolution measurement?

Created on Jan 13, 2011 12:10:54 PM by  Daniel Zobel [Product Manager]

Last change on Jan 13, 2011 2:10:42 PM by  Patrick Hutter [Paessler Support] (7,225) 3 3



We use IP addresses and not DNS-names, but the ping time is affected. With PRTG V8.1 we have 2-3ms average. With PRTG V8.2.1.1931 we have 0ms. On other devices it decreases from 2-3 to 1ms Why?

Regards Michael (DCC)

Created on Feb 7, 2011 7:14:46 AM



PRTG Ping sensors no longer use the previous, proprietary time measurement mechanism but the roundtrip time returned by the Ping algorithm.

Created on Feb 9, 2011 3:25:19 PM by  Patrick Hutter [Paessler Support] (7,225) 3 3

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