Which company owns MAC address prefix 34:40:B5?

MAC address prefix 34:40:B5 is registered to IBM in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 34:40:B5 has a network interface built by IBM.

What is the OUI 34:40:B5?

34:40:B5 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to IBM. It covers every address from 34:40:B5:00:00:00 to 34:40:B5:FF:FF:FF, or 16,777,216 addresses in total. It is also written 34-40-B5.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 34:40:B5:00:00:00 that is 34:40:B5 — 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 IBM located?

IBM is listed at 3039 E Cornwallis Rd Research Triangle Park NC US 27709 in the IEEE OUI registry entry for 34:40:B5. This is the address the organization registered with the IEEE, which may differ from its current operating address.

How many MAC prefixes does IBM own?

IBM holds 4 OUI prefixes in the IEEE registry, of which 34:40:B5 is one. A device made by IBM could carry a MAC address from any of them.

IBM

MAC address prefix 34:40:B5 is registered to IBM in the IEEE OUI registry. Any device whose MAC address begins with 34:40:B5 has a network interface built by IBM. 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 34:40:B5:00:00:00 to 34:40:B5:FF:FF:FF.

OUI prefix: 34:40:B5
Hyphen form: 34-40-B5
MAC range: 34:40:B5:00:00:00 – 34:40:B5:FF:FF:FF
Addresses in block: 16,777,216
Organization: IBM
Address: 3039 E Cornwallis Rd Research Triangle Park NC US 27709
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 IBM

IBM holds 4 OUI prefixes in total. A device with this exact prefix could just as well carry any of these:

Assignment history (2)

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 "IBM"
archived source →
2026-07-17Assigned to "IBM"

Nearby in the registry

The prefixes assigned immediately before and after 34:40:B5:

FAQ

Which company owns MAC address prefix 34:40:B5?: MAC address prefix 34:40:B5 is registered to IBM in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 34:40:B5 has a network interface built by IBM.
What is the OUI 34:40:B5?: 34:40:B5 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to IBM. It covers every address from 34:40:B5:00:00:00 to 34:40:B5:FF:FF:FF, or 16,777,216 addresses in total. It is also written 34-40-B5.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 34:40:B5:00:00:00 that is 34:40:B5 — 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 IBM located?: IBM is listed at 3039 E Cornwallis Rd Research Triangle Park NC US 27709 in the IEEE OUI registry entry for 34:40:B5. This is the address the organization registered with the IEEE, which may differ from its current operating address.
How many MAC prefixes does IBM own?: IBM holds 4 OUI prefixes in the IEEE registry, of which 34:40:B5 is one. A device made by IBM could carry a MAC address from any of them.