Target Display Mode from a 2016 MacBook to a 2011 27" iMac
It's not possible to use Target Display Mode to connect a MacBook (Early 2016) to a 27" iMac (2011)

For the Mid-2011 through Mid-2014 iMacs, you need a Thunderbolt cable and Thunderbolt isn't available on the Early 2016 MacBooks

From the Thunderbolt Support Page


  A Mac notebook or desktop with a Mini DisplayPort or Thunderbolt port.
  


From the MacBook (Early 2016) Tech Specs Page:


USB-C port with support for: 


Charging
USB 3.1 Gen 1 (up to 5 Gbps)
Native DisplayPort 1.2 video output
VGA output using USB-C VGA Multiport Adapter (sold separately)
HDMI video output using USB-C Digital AV Multiport Adapter (sold separately)



Thunderbolt is not supported on this USB-C port.