What this means
The IEEE assigned the MA-L block 40040C to A&T. 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 40:04:0C, it is A&T hardware.
Frequently Asked Questions
Who owns MAC prefix 40040C?
40040C is registered to A&T 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. A&T's block covers 16,777,216 addresses.
What devices use 40040C?
Any network device with a MAC address starting 40:04:0C was manufactured by or for A&T.