MAC OUI Vendor Lookup
From vendor documentationPaste a MAC or a bare OUI and get the registered vendor, the assignment type (MA-L, MA-M or MA-S) and whether the address is globally unique or locally administered. Curated offline subset of the IEEE registry.
Input
A full address, or 2–9 hex digits of a prefix: 005056, 00:50:56, 0050.56.
About this table
998 prefixes loaded
The table is built into the page, so the lookup works offline and no address leaves the browser. It covers the IEEE MA-L blocks (24-bit vendor assignments) plus the MA-M and MA-S rows this build carries.
A miss means “not in this build”, not “not a real vendor”. The lookup never guesses: if the prefix is absent it says so rather than inventing a name.
An MA-M or MA-S parent block is deliberately not listed as a vendor — those are 24-bit identifiers the IEEE holds itself, so reporting one would name the IEEE as the manufacturer.
Vendor
- Vendor
- VMware
- Matched prefix
- 005056
- Assignment type
- MA-L
- Block size
- 2^24 (16,777,216) addresses
24 of the 48 address bits are the manufacturer prefix.
vSphere / ESXi and vCenter-managed VMs — the one you will see most often.
Address assignment
- Assignment
- Globally unique (OUI)
- OUI bits
- 005056
Bit 1 of the first octet is clear, so the top 24 bits are a registered IEEE assignment and the vendor lookup is meaningful.
How this was resolved
The lookup order the IEEE registry requires
- Prefix length used
- 6 hex digits (24 bits)
- Block for that length
- MA-L — longest match wins
- Why longest first
- MA-M and MA-S blocks are carve-outs inside larger blocks, so a 28- or 36-bit assignment is more specific than the 24-bit OUI that contains it.
Frequently asked
- Why does a MAC start with 02 or 0A when no vendor uses that prefix?
- Bit 1 of the first octet is the locally-administered bit. When it is set, software chose the address — a hypervisor, a container runtime such as Docker (02:42:AC), or an administrator — so the first 24 bits are not a registered vendor assignment at all.
- What is the difference between MA-L, MA-M and MA-S?
- They are the three IEEE assignment sizes: MA-L is a 24-bit block of 16,777,216 addresses, MA-M a 28-bit block of 1,048,576, and MA-S a 36-bit block of 4,096 that is usually IoT silicon. A lookup has to try all three, longest prefix first, because the smaller blocks live inside larger ones.
- Is this the complete IEEE registry?
- It is the set of prefixes this build ships, which is the IEEE MA-L vendor blocks plus the MA-M and MA-S rows listed. The full registry adds tens of thousands of assignments and is revised weekly, so a miss means "not in this build", not "not a real vendor".
- Can I look up a MAC that is not fully formed, like a bare OUI?
- Yes. Two to nine hex digits are accepted, so 005056, 00:50:56 and 0050.56 all resolve. The tool treats a short fragment as a prefix and shows which table row matched.
- Does the lookup send my MAC anywhere?
- No. The whole table is compiled into the page and the match runs in your browser, so it works offline and no address leaves the machine.
Next
- MAC Address Format ConverterPaste a MAC in any notation and get every convention back at once — Cisco, Linux, Windows, bare hex — plus the multicast and locally-administered bits and the EUI-64 / IPv6 link-local form.
- DHCP Option 43 GeneratorBuild the DHCP option 43 value that points access points at their wireless controller, with the per-sub-option breakdown, the Cisco dotted hex, a per-vendor CLI, and a generic TLV builder for anything not covered.