What this means
The IEEE assigned the MA-M block 8411C29 to C TECH BILISIM TEKNOLOJILERI SAN. VE TIC. A.S.. Every network interface they manufacture under this block has a MAC address beginning with these digits, followed by a unique per-device identifier. If a device on your network shows a MAC starting 84:11:C2:9, it is C TECH BILISIM TEKNOLOJILERI SAN. VE TIC. A.S. hardware.