Which company owns MAC address prefix 40:DE:AD?

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

What is the OUI 40:DE:AD?

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

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 40:DE:AD:00:00:00 that is 40:DE:AD — 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 Juniper Networks located?

Juniper Networks is listed at 1133 Innovation Way Sunnyvale CA US 94089 in the IEEE OUI registry entry for 40:DE:AD. This is the address the organization registered with the IEEE, which may differ from its current operating address.

How many MAC prefixes does Juniper Networks own?

Juniper Networks holds 211 OUI prefixes in the IEEE registry, of which 40:DE:AD is one. A device made by Juniper Networks could carry a MAC address from any of them.

Juniper Networks

MAC address prefix 40:DE:AD is registered to Juniper Networks in the IEEE OUI registry. Any device whose MAC address begins with 40:DE:AD has a network interface built by Juniper Networks. 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 40:DE:AD:00:00:00 to 40:DE:AD:FF:FF:FF.

OUI prefix: 40:DE:AD
Hyphen form: 40-DE-AD
MAC range: 40:DE:AD:00:00:00 – 40:DE:AD:FF:FF:FF
Addresses in block: 16,777,216
Organization: Juniper Networks
Address: 1133 Innovation Way Sunnyvale CA US 94089
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 Juniper Networks

Juniper Networks holds 211 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.

2020-03-21Assigned to "Juniper Networks"
archived source →
2026-07-17Assigned to "Juniper Networks"

Nearby in the registry

The prefixes assigned immediately before and after 40:DE:AD:

FAQ

Which company owns MAC address prefix 40:DE:AD?: MAC address prefix 40:DE:AD is registered to Juniper Networks in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 40:DE:AD has a network interface built by Juniper Networks.
What is the OUI 40:DE:AD?: 40:DE:AD is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Juniper Networks. It covers every address from 40:DE:AD:00:00:00 to 40:DE:AD:FF:FF:FF, or 16,777,216 addresses in total. It is also written 40-DE-AD.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 40:DE:AD:00:00:00 that is 40:DE:AD — 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 Juniper Networks located?: Juniper Networks is listed at 1133 Innovation Way Sunnyvale CA US 94089 in the IEEE OUI registry entry for 40:DE:AD. This is the address the organization registered with the IEEE, which may differ from its current operating address.
How many MAC prefixes does Juniper Networks own?: Juniper Networks holds 211 OUI prefixes in the IEEE registry, of which 40:DE:AD is one. A device made by Juniper Networks could carry a MAC address from any of them.