Strange MAC addresses starting FA:8F:CA without OUI in your network? They are Locally Administered Addresses and likely from Google.
Posted by jpluimers on 2019/01/07
A while ago, I write about Locally Administered Addresses: a few series of MAC addresses you can use on your local network: MAC address ranges safe for testing purposes (Locally Administered Address).
A while ago, I found ones in my network and ones in my WiFi SSID survey starting with FA:8F:CA. They did not show up in the Wireshark · OUI Lookup Tool nor their manufacturer database.
But with bit 7 turned off they start with F8:8F:CA which does show up as “F8:8F:CA Google, Inc.”
They appear to be Google devices, in my case Google ChromeCast ones, though they can also be Google Home ones.
Google does “magic” with networks, just look at a few of the links here:
- [Archive.is] Faster Chromecast network identification · Issue #4 · BishopFox/rickmote
- [WayBack] Hidden Google Fiber WiFi Network?
- [Archive.is] Weird “Google Fiber” hotspots with no SSID that appear on the the same channel as my network, just after my Chromecasts attach to it. Anyone else see these? : Chromecast
- [WayBack] Mysterious fa:8f:ca:xx:xx:xx MAC address is Google Home’s guest mode – Ubiquiti Networks Community
- [Archive.is] chromecast sends hidden SSID – Google Product Forums
- [Archive.is] Chromecast causing interference in the Wifi – Google Product Forums
–jeroen
The Wiert Corner - irregular stream of stuff 
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