What’s That Device on Your Network?
You’re looking at your router’s client list and there’s a device you don’t recognize. The MAC address is DC:A6:32:XX:XX:XX. Is it someone’s phone? A smart thermostat? Or an unauthorized device that shouldn’t be there?
The first three octets of a MAC address (the OUI — Organizationally Unique Identifier) are assigned to manufacturers by the IEEE. DC:A6:32 belongs to Raspberry Pi. Mystery solved — it’s that Pi-hole you set up six months ago and forgot about.
Paste any MAC address in any format (colons, hyphens, dots, or plain) and get the manufacturer name. The lookup runs against a bundled copy of the full IEEE OUI registry (around 39,000 vendor prefixes) right in your browser — no data leaves your device. The dataset loads on your first lookup, so the very first result takes a moment longer.
Network Security Applications
Rogue device detection. Your office network should only have Dell laptops, HP printers, and Cisco access points. A MAC address with an OUI belonging to a smartphone manufacturer that nobody recognizes? Investigate.
IoT inventory. Smart cameras, environmental sensors, badge readers, smart plugs — they all have MAC addresses. Use OUI lookups to categorize the IoT devices on your network by manufacturer.
Incident investigation. During a security incident, you’ve got MAC addresses from network logs. OUI lookups tell you what kind of hardware was involved. A Raspberry Pi OUI on a corporate network where no Pi should exist is a red flag.
BYOD policy enforcement. Your company allows personal devices but wants visibility. MAC address vendor lookups help classify which devices are corporate-managed (Dell, Lenovo) versus personal (Apple, Samsung).
Why “Unknown Vendor” Happens
MAC address randomization. iOS 14+ and Android 10+ randomize MAC addresses when scanning for WiFi networks. The randomized addresses don’t match any real OUI because they’re generated locally. If a device is connected to your network (not just scanning), it usually uses its real MAC.
Very new or niche manufacturers. The bundled database mirrors the IEEE OUI registry, so it covers tens of thousands of prefixes — but a brand-new allocation registered after this copy was built won’t be in it yet. Re-check against a live IEEE lookup if a prefix you expect is missing.
Virtual machines. VMs often use vendor-specific OUI prefixes (00:50:56 for VMware, 52:54:00 for KVM), but some use randomly generated MACs.
The MAC address is entered in any common format — 00:1A:2B:3C:4D:5E, 00-1A-2B-3C-4D-5E, 001A.2B3C.4D5E, or 001A2B3C4D5E all work.
For IP-level information, the IP Address Lookup provides geolocation and ISP data. The CIDR Range Calculator helps with subnet planning.