MAC / OUI vendor lookup
Look up a MAC address's OUI against a small bundled table of 16 well-known prefixes, not the IEEE registry (2.9M+ entries, updated continuously, no offline way to bundle it here). "Not in bundled list" means exactly that, not "no vendor exists."
MAC / OUI vendor lookup takes a MAC address and prints it in colon form, its first three bytes as the OUI, and the vendor those bytes belong to. Where the locally-administered bit is set the lookup is skipped, since such an address came from no vendor block. The bundled table holds 16 prefixes, so unlisted means unlisted.
Questions
Where does the vendor data come from?
A small table bundled with the site, currently 16 OUIs, hand picked for being well documented and stable. It is not the IEEE registry, which is a multi megabyte, continuously updated file with millions of entries and no offline way to ship it here. The tool blurb and its output both say so.
Why is my device vendor not listed?
Almost always because it is not in those 16 entries. The output says "not in this tool's bundled table of 16 OUIs", which means exactly that and not that no vendor owns the prefix. The bundled set leans towards virtualization vendors such as VMware, VirtualBox, Hyper-V, Xen and QEMU, plus Cisco, Intel, Raspberry Pi, Sun and Google.
Why does it skip the lookup for some addresses?
Because the locally administered bit is set. That address was not assigned from a vendor OUI block at all, so a vendor answer would be meaningless. The tool says the bit is set and stops, rather than reporting a coincidental table hit.
What else does it print?
The MAC in colon notation, the OUI as its first three bytes in colon notation, the vendor line, and a note when the multicast bit is set saying the address is a group address rather than a single interface. That last one comes from the address bits, so it is right regardless of the table.
Can I search the full IEEE list here?
No, and no request is made to look one up. If the prefix is not in the bundled table you will need the IEEE registry or another source. For pure reformatting and the address bits, use the MAC address formatter.