Realtek is a striking case: despite an enormous installed base, it holds only 2 distinct IEEE blocks under the exact registrant "REALTEK SEMICONDUCTOR CORP." — the dominant 00:E0:4C MA-L and one newer MA-S — based in Hsinchu, Taiwan. The critical analyst caveat is that a Realtek OUI identifies the *chipset*, not a "Realtek-branded" device. Realtek Ethernet and Wi-Fi controllers are embedded in third-party products everywhere: generic motherboards, cheap NICs, USB-Ethernet dongles, and countless OEM devices. The product families behind these MACs include the RTL8111/8168 Gigabit Ethernet, RTL8125 2.5G Ethernet, RTL8188/8192 Wi-Fi, and various USB-Ethernet controllers. Because so few blocks (chiefly 00:E0:4C) serve such a vast device population, the per-block address density is extremely high. One related trap: the prefix 52:54:00 is widely associated with Realtek/QEMU virtual NICs, but it is a locally-administered/randomized range (typically a VM or randomized MAC), not a Realtek IEEE assignment, and should not be mapped to Realtek. For triage, do not infer device type or brand from a Realtek OUI — it appears on everything from desktop motherboards to USB dongles; pair it with other fingerprints before classifying the asset.
- IEEE assignment
- 00:E0:4C (MA-L) and one MA-S → REALTEK SEMICONDUCTOR CORP., registered Hsinchu, Taiwan [Confirmed] — IEEE MA-L + MA-S
- Registry / block size
- MA-L plus MA-S; only 2 distinct blocks under this exact registrant — 00:E0:4C (MA-L) and 8C:1F:64:D5:A (MA-S) [Confirmed assignments] — maclookup.app (IEEE-derived). NOTE: IEEE's public OUI data publishes NO assignment/registration date (oui.csv columns are only Registry, Assignment, Organization Name, Organization Address); any "date registered" from third-party tools is a database artifact, not an IEEE fact.
- HQ / country
- 1F, No. 11, Industry E. Rd. IX, Hsinchu 300, Taiwan [Confirmed] — IEEE MA-L
- Company status
- active [Confirmed] — realtek.com
- Device types
- Ethernet and Wi-Fi chipsets embedded in third-party products — generic motherboards, cheap NICs, USB-Ethernet dongles, OEM devices [Confirmed] — maclookup.app
- Notable products
- RTL8111/8168 Gigabit Ethernet, RTL8125 2.5G Ethernet, RTL8188/8192 Wi-Fi, USB-Ethernet controllers
- Special note
- Critical caveat — a Realtek OUI identifies the CHIPSET, not a "Realtek-branded" device; the overwhelming majority of Realtek MACs sit on third-party hardware. So few blocks (chiefly 00:E0:4C) for such a large installed base = extremely high per-block density. The prefix 52:54:00 (often cited as Realtek/QEMU virtual NIC) is a locally-administered/randomized range, NOT a Realtek IEEE assignment. [Confirmed] — maclookup.app/macaddress/525400/mac-address-details
- Related vendors
- none for OUI purposes
- Analyst note
- Do not infer device type or brand from a Realtek OUI — it appears on everything from desktop motherboards to USB dongles; pair it with other fingerprints before classifying the asset.