mDNSResponder ... a symptom ?

Was getting a high CPU utilisation ( > 30% ) on the process mDNSResponder over the last 3 days and Wireless was slowing down to a crawl.
Also noticed that I had incoming traffic at above 60 Kpbs, when all applications were closed.

iStumbler indicated 70% noise on the WiFi on some occasions, so I started looking for the " noisemaker " and went disabling all other WiFi enabled devices and bluetooth devices.... I even unplugged the microwave.
( yeah yeah ... I know .... )

Started changing WiFi channels on the Wireless modem provided by the ISP, to no avail.
Started to switch between g and N networks, no joy.

Then I had a lucky break as I connected with a normal Ethernet cable and that connection dropped as well, so now I knew it was the modem/ISP

The ISP sent a technician over and he diagnosed the WiFi chip in the modem and being the culprit, it was freaking out for no reason.
( apparently this has a technical name, but I didn't understand him )
Modem replaced, all is well.


Just thought I would share the 2 symptoms and the root cause in case anyone runs into the same symptoms.

Cheers ... McBie

Would have been interesting to see a Wireshark capture while this symptom was occurring. Probably a firmware issue with the modem - perhaps errantly flooding multicast queries for no good reason?

Yeah ... you are right ... I should have seized the opportunity and install Wireshark for that, but I was so hyped up to get this solved that I did not think off that.
( Kids are preparing their university exams and they need the internet for research. )

Modem worked fine for 2 years, so I don't think firmware would have solved the issue .... then again ... maybe changed in the environment that triggered this.
( more and more neighbors are having WiFi )

Thanks for the tip.

Cheers ... McBie

mDNSResponder

Well, I have a similar problem with mDNSResponder. Every Saturday, when the weekly maintenance scripts are automatically run in background, my internet connection fails. When I check the CPU load, the mDNSResponder is eating more CPU than it usually does. My solution is to kill the mDNSResponder process, which is then restarted automatically, and the internet connection is back to normal. Maybe the real cause is the modem, but I have no way to check this. Anyways, I thought I would share this weekly solution to the problem...