That is a combination of Windows Deployment Services(WDS), System Center Config Manager(SCCM), and Active Directory (AD). You can advertise an Operating System Deployment (OSD) in SCCM for a specific OU in AD, and move the specific PC into that OU. The next time it is booted, imaging will be forced. SCCM leverages WDS to get this accomplished.
So, while WDS does allow PXE booting and imaging across the network, it cannot be quite as automated as that without SCCM. Normally, you would boot to PXE manually and select the boot image. Once the boot image loads, you might have other options to choose/setup before the image applies.
The settings for how a client responds to the PXE boot can be found in the left page of WDS, select the server and right click. Choose properties, then the boot tab.
Hope this helps,
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Windows Outreach Team - IT Pro