D8:21:DA

D8:21:DA is registered to SERNET (SUZHOU) TECHNOLOGIES CORPORATION, CN. That page carries the full record: every prefix the organisation holds, its registered address, and the research behind the entry.

D8:21:DA is an OUI: the first three octets of a MAC address. Every address beginning with these octets was issued from this block. The remaining three octets are assigned by the block holder to individual network interfaces, so one 24-bit block spans 16,777,216 addresses.

The IEEE Registration Authority is the source of record for these assignments. A 24-bit block can belong to one organisation outright, or be divided into smaller MA-M and MA-S ranges held by several unrelated registrants.

To identify the holder of a specific address, run the full MAC through the MAC address lookup. The vendor directory lists the organisations with a researched profile on this site.