Hi,

I get inconsistent results between MS-DOS and PRTG ping.

When I use MS-DOS, I get occasionally a round-trip time well over 1 msec. But with PRTG, I get that 50% of the time.

Is there something I am missing?

PRTG :

2018-01-23 11:38:18 AM0 msec0 msec0 msec0 %0 %100 %
2018-01-23 11:37:48 AM14 msec0 msec37 msec0 %0 %100 %
2018-01-23 11:37:18 AM0 msec0 msec0 msec0 %0 %100 %
2018-01-23 11:36:48 AM16 msec1 msec41 msec0 %0 %100 %
2018-01-23 11:36:18 AM0 msec0 msec1 msec0 %0 %100 %
2018-01-23 11:35:48 AM7 msec0 msec21 msec0 %0 %100 %
2018-01-23 11:35:18 AM0 msec0 msec0 msec0 %0 %100 %
2018-01-23 11:34:48 AM6 msec0 msec20 msec0 %0 %100 %
2018-01-23 11:34:18 AM0 msec0 msec0 msec0 %0 %100 %

CMD:

Reply from 192.168.2.1: bytes=32 time<1ms TTL=64
Reply from 192.168.2.1: bytes=32 time<1ms TTL=64
Reply from 192.168.2.1: bytes=32 time<1ms TTL=64
Reply from 192.168.2.1: bytes=32 time<1ms TTL=64
Reply from 192.168.2.1: bytes=32 time<1ms TTL=64
Reply from 192.168.2.1: bytes=32 time<1ms TTL=64
Reply from 192.168.2.1: bytes=32 time<1ms TTL=64
Reply from 192.168.2.1: bytes=32 time<1ms TTL=64
Reply from 192.168.2.1: bytes=32 time<1ms TTL=64
Reply from 192.168.2.1: bytes=32 time<1ms TTL=64
Reply from 192.168.2.1: bytes=32 time<1ms TTL=64
Reply from 192.168.2.1: bytes=32 time=30ms TTL=64
Reply from 192.168.2.1: bytes=32 time=1ms TTL=64
Reply from 192.168.2.1: bytes=32 time<1ms TTL=64
Reply from 192.168.2.1: bytes=32 time<1ms TTL=64
Reply from 192.168.2.1: bytes=32 time<1ms TTL=64
Reply from 192.168.2.1: bytes=32 time<1ms TTL=64
Reply from 192.168.2.1: bytes=32 time<1ms TTL=64
Reply from 192.168.2.1: bytes=32 time<1ms TTL=64
Reply from 192.168.2.1: bytes=32 time<1ms TTL=64
Reply from 192.168.2.1: bytes=32 time<1ms TTL=64
Reply from 192.168.2.1: bytes=32 time<1ms TTL=64
Reply from 192.168.2.1: bytes=32 time<1ms TTL=64
Reply from 192.168.2.1: bytes=32 time<1ms TTL=64
Reply from 192.168.2.1: bytes=32 time<1ms TTL=64
Reply from 192.168.2.1: bytes=32 time<1ms TTL=64

Article Comments

Hi Superbobby,

Are you really using MS-DOS to send the Pings, or did you start a command line on the host where PRTG is installed?

PRTG uses the Windows API to send Pings to target devices. As the command line also shows one of these spikes, it does not necessarily need to be wrong that PRTG also receives these spikes; the scanning interval of 30 seconds is higher than the interval of Pings via CMD. If the command line is started on the very same host as the PRTG probe, do the spikes still occur if you stop the Pings via the CMD?

Best regards, Felix


Jan, 2018 - Permalink

Hi,

I started a command line on the host where PRTG is installed. Sorry, MS-DOS is what some people still call it.

The spikes occur in all time. It does not affect the results if I ping simultaneously using CMD. I was not doing any ping when I captured the PRTG results (see up here).

I am aware of the 30 seconds interval. I did some random ping from CMD and the results are still the same. Using CMD from a different computer on the same LAN, I get similar results.

The device I am pinging is a Sonicwall SOHO firewall.


Jan, 2018 - Permalink

I got the answer.

Since I am pinging a network device (Sonicwall Firewall)...

"...pinging to a an loopback interface on a switch will always give you varying results , only a ping end end is valid ...it will not be accurate as it is not giving priority to the icmp packet"

REF


Jan, 2018 - Permalink

Hi Superbobby,

Thanks for sharing your findings, makes a lot of sense then.

Best regards, Felix


Jan, 2018 - Permalink