What this means
The IEEE assigned the MA-L block DC9840 to Microsoft Corporation. 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 DC:98:40, it is Microsoft Corporation hardware.
Frequently Asked Questions
Who owns MAC prefix DC9840?
DC9840 is registered to Microsoft Corporation 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. Microsoft Corporation's block covers 16,777,216 addresses.
What devices use DC9840?
Any network device with a MAC address starting DC:98:40 was manufactured by or for Microsoft Corporation.