What this means
The IEEE assigned the MA-L block 84A991 to Cyber Trans Japan Co.,Ltd.. 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:A9:91, it is Cyber Trans Japan Co.,Ltd. hardware.
Frequently Asked Questions
Who owns MAC prefix 84A991?
84A991 is registered to Cyber Trans Japan Co.,Ltd. in the IEEE MA-L registry.
What does the MA-L registry type mean?
An MA-L assignment, the IEEE's original OUI format, gives the vendor the first three octets and 16,777,216 device addresses under them. Cyber Trans Japan Co.,Ltd.'s block covers 16,777,216 addresses.
What devices use 84A991?
Any network device with a MAC address starting 84:A9:91 was manufactured by or for Cyber Trans Japan Co.,Ltd..