Who owns MAC prefix 00A03D?

00A03D is registered to OPTO-22 in the IEEE MA-L registry.

What devices use 00A03D?

Any network device with a MAC address starting 00:A0:3D was manufactured by or for OPTO-22.

MA-L · OUI prefix

OPTO-22

Any MAC address starting 00:A0:3D is registered to OPTO-22 in US.

OUI prefix	00A03D
Vendor	OPTO-22
Registry	MA-L (24-bit, large block)
Country	US
Example MAC	00:A0:3D:00:00:00

What this means

The IEEE assigned the MA-L block 00A03D to OPTO-22. 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 00:A0:3D, it is OPTO-22 hardware.

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