Which company owns MAC address prefix 00:21:3E?

MAC address prefix 00:21:3E is registered to TomTom International BV in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 00:21:3E has a network interface built by TomTom International BV.

What is the OUI 00:21:3E?

00:21:3E is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to TomTom International BV. It covers every address from 00:21:3E:00:00:00 to 00:21:3E:FF:FF:FF, or 16,777,216 addresses in total. It is also written 00-21-3E.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 00:21:3E:00:00:00 that is 00:21:3E — and look that prefix up in the IEEE OUI registry. If the second-lowest bit of the first octet is set, the address is locally administered (a randomized or private MAC), which belongs to no manufacturer and will not resolve; modern phones and laptops use these by default on each network.

Where is TomTom International BV located?

TomTom International BV is listed at Oosterdoksstraat 114 Amsterdam North Holland NL 1011 DK in the IEEE OUI registry entry for 00:21:3E. This is the address the organization registered with the IEEE, which may differ from its current operating address.

How many MAC prefixes does TomTom International BV own?

TomTom International BV holds 2 OUI prefixes in the IEEE registry, of which 00:21:3E is one. A device made by TomTom International BV could carry a MAC address from any of them.

TomTom International BV

MAC address prefix 00:21:3E is registered to TomTom International BV in the IEEE OUI registry. Any device whose MAC address begins with 00:21:3E has a network interface built by TomTom International BV. This prefix (the OUI, or Organizationally Unique Identifier) is assigned by the IEEE and is the first three octets of the address — it covers every MAC from 00:21:3E:00:00:00 to 00:21:3E:FF:FF:FF.

OUI prefix: 00:21:3E
Hyphen form: 00-21-3E
MAC range: 00:21:3E:00:00:00 – 00:21:3E:FF:FF:FF
Addresses in block: 16,777,216
Organization: TomTom International BV
Address: Oosterdoksstraat 114 Amsterdam North Holland NL 1011 DK
Source: IEEE OUI registry

Have a full MAC address? Look it up— we'll also tell you if it's a randomized (private) address rather than a real manufacturer prefix.

Other prefixes from TomTom International BV

TomTom International BV holds 2 OUI prefixes in total. A device with this exact prefix could just as well carry any of these:

24:E9:27

Assignment history (3)

The IEEE registry publishes current state only — this is the change record we've kept since we started tracking it daily.

2016-07-29Assigned to "TomTom"
archived source →
2020-11-28Renamed from "TomTom" to "TomTom International BV"
archived source →
2026-07-17Assigned to "TomTom International BV"

Nearby in the registry

The prefixes assigned immediately before and after 00:21:3E:

FAQ

Which company owns MAC address prefix 00:21:3E?: MAC address prefix 00:21:3E is registered to TomTom International BV in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 00:21:3E has a network interface built by TomTom International BV.
What is the OUI 00:21:3E?: 00:21:3E is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to TomTom International BV. It covers every address from 00:21:3E:00:00:00 to 00:21:3E:FF:FF:FF, or 16,777,216 addresses in total. It is also written 00-21-3E.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 00:21:3E:00:00:00 that is 00:21:3E — and look that prefix up in the IEEE OUI registry. If the second-lowest bit of the first octet is set, the address is locally administered (a randomized or private MAC), which belongs to no manufacturer and will not resolve; modern phones and laptops use these by default on each network.
Where is TomTom International BV located?: TomTom International BV is listed at Oosterdoksstraat 114 Amsterdam North Holland NL 1011 DK in the IEEE OUI registry entry for 00:21:3E. This is the address the organization registered with the IEEE, which may differ from its current operating address.
How many MAC prefixes does TomTom International BV own?: TomTom International BV holds 2 OUI prefixes in the IEEE registry, of which 00:21:3E is one. A device made by TomTom International BV could carry a MAC address from any of them.