I recommend you UnHackMe - Ultimate Malware Killer for fast malware removal:
Free Download Fully Functional 30-day Trial. No credit card is required.
Reviews. EULA. Privacy Policy. Uninstall.
The program questdns.exe is used for the hidden penetration into PC and its remote administration.
UnHackMe is recommended as a reliable program for solving the problem with questdns.exe.
Download for free: http://www.unhackme.com