How to find out which app uses mdnsd My battery life has dropped massively recently and there's an unrecognised app 'mdnsd' that's using a fair percentage of it.

AFAIK mdnsd broadcasts info about services running to a local network, but I can't think what APIs would need that. How can I find out which app is using this?
This is a bug associated with firefox. From this source: https://bugzilla.mozilla.org/show_bug.cgi?id=1215012.

It is also suspected to be caused by the patch Support Multicast DNS (mDNS)

Further tests showed these results:

 Actual results:

Excessive battery usage when using Firefox beta.
Phone Power setting shows MSNSD with increasing usage.


This issue was mainly noted in beta version of firefox and version 42.

Several users have complained about the issue and this how they resolved it:


  Install this new version, run it once, and the mdnsd process starts
  busily running your battery life down. It took my S5 from 17 or 20
  hours before the battery would run out to 4 hours. This is true
  whether or not Firefox is running in the background. All the
  complaints on the web about this start around November 2014 time frame
  with complaints about the two other random apps, but only a couple,
  and a comment on the Mozilla Bugzilla platform that there was a report
  of extreme battery usage sometime in July of 2015


Source:  What is MDNSD and how do I get rid of it?

Uninstalling firefox proved to be the solution:


  So by uninstalling Firefox, the mdnsd process stopped draining the
  battery for the rest of the day. After recharging the battery
  overnight and beginning to use the phone the following day, the
  Battery usage report no longer shows the mdnsd process!


Source: Mdnsd killing battery?

Probably the issue was subsequently fixed with newer versions of the browser.