Xbox Live/Machine Account
All Xboxes that communicate on Xbox Live will have a Machine Account - it's generated the first time a user performs a connection test from the factory on an Xbox Live dashboard (4920 or later).
Machine Account Creation Service
The first time an Xbox connects to Xbox Live from the factory, it'll connect to MACS.XBOXLIVE.COM and use a pre-shared key based from the Online Key, HDD Key, and a unique key present in all Xbox Live binaries. The server will either return an error message, or return a valid machine account for future authentication.
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