Why is "mdnsd" draining my battery and how to stop it? This process (mdnsd) had been draining my battery for a few weeks. I have not been able to find a solution after a lot of search. 

I don't have any drone app, Facebook app or Firefox, although it's true the issue started more or less when I installed the Firefox app. But I have uninstalled it, rebooted my phone and the issue is still there which makes me think Firefox maybe didn't have anything to do with this.

Any ideas? I have an LG G2, Android 4.4.2
It seems like it is the daemon for multicast DNS. I have the same issue as OP and Trevor. My solution is the following (assuming you have a rooted device). If you have adb, then do step 2 over that, it is more comfortable to type on a keyboard ;)


Install a Terminal Emulator
Create a shellscript with the content su -c "kill $(pgrep mdnsd)"
Run it everytime you see fast battery drainage as this is a symptom of a running mdnsd. Confirm the prompt of SuperSU to grant root permissions to the script.


What the script does:

su -c "kill $(pgrep mdnsd)"
^      ^    ^ ^
|      |    | |
|      |    | +- Search the process list for the phrase "mdnsd" and return the process id
|      |    |
|      |    +- Spawn a subshell and execute contained command and return its output
|      |
|      +- Stop the process with the process id specified after kill
+- run the command specified after -c with superuser privileges