Windows 10 Unattended install media – Part 1: Basics

Boot & forget

Of all the operating systems I know, Windows is the most versatile and flexible when it comes to setting up totally automated, unattended “hands free” install media. Pretty much everything you might want to do can indeed be done. It’s just a matter of knowing how!

In this series of posts, we will customize a Windows 10 Spring Creators Update version 1803 image, create an answer file to automate Windows setup and another answer file to do the same for OOBE.  As our reference machine — that is, the machine used to customize and capture the image — we will use a Hyper-V virtual machine.

The end product will be an ISO image which can be used for traditional installations from a USB flash drive as well as with various deployment tools. This install media will perform a 100% unattended, “hands-free” Windows setup and installation. In a traditional clean install we need only boot from the installation media then forget it. Depending on the hardware involved, in from 10 to 30 minutes you have a fresh, clean-installed, highly customized Windows 10 ready and waiting for you to sign in. This means installation proceeds all the way from boot to the sign-in screen without requiring a single key press.

First, some boring background.

Windows Configuration Passes

Since the dawn of the Windows NT product line, Windows setup has witnessed very few changes. For over a decade (since Vista appeared in January 2007 for public release) it has remained almost entirely the same.

Windows setup occurs in a series of so-called configuration passes, which follow one another in a specific and pre-ordained order. There are 7 configuration passes:

The preceding diagram comes from a Microsoft TechNet article. In that same article you can find a brief description of each of these configuration passes. To keep this somewhat shorter I won’t Copy & Paste the article. Rather, I recommend you read it all the way through. Although understanding the configuration passes is not required to follow these instructions, it might help you to understand the logic behind the processes involved.

For our purposes, we only need Pass 1 WindowsPE, Pass 3 Generalize, Pass 4 Specialize and finally Pass 7 OobeSystem. We will use our answer file autounattend.xml to configure Pass 1 and unattend.xml for the other three passes.


Most of you geeks are familiar with Sysprep, or as it is officially called, the Windows System Preparation Tool.It was first introduced with Windows NT 4.0, with most of its features in place by the time Vista was released.

A bit off topic: A few years ago, Microsoft apparently thought to deprecate Sysprep. Their idea was to use their new tool Windows ICD (Imaging and Configuration Designer, usually abbreviated WICD and pronounced “wicked”) instead. When the preview version of WICD was released, it had the option to create a WIM image and basically do everything for which we had previously used Sysprep. In fact, WICD did an excellent job. I got very interested in WICD and even made a video about using WICD to create a custom image instead of Sysprep back in March 2015, but never published it. That was fortuitous, because only a short time later, for reasons unknown to me, the imaging part of WICD was suddenly removed in later preview versions and does not appear in the final release. Sysprep won the battle and is here to stay. In the following screenshot (an extract from that unpublished video) you can see the now-removed imaging option in WICD:

Imaging option was included in preview versions of WICD. Click to view enlarged in new tab.

Interestingly, the imaging part is still used in its application name as shown in Start and Program Files folder, although the application itself shows the name without the word Imaging. In the following screenshot, notice how the name of the application is still shown in the Start menu, but absent in how the application itself shows its name:

The word “Imaging” still appears in Start although it’s removed from application itself. Click to view enlarged in a new tab.

Back to Sysprep. The magic happens when the /generalize switch is used with the Sysprep command. It prepares a Windows installation for imaging, removing all unique system information, resetting SIDs, removing all existing restore points and clearing event logs. In addition, the built-in admin account  — which in most cases is used to customize and prepare the image — will be disabled and hidden from the sign-in screen.

The Windows image, when generalized with Sysprep, is a hardware independent image. Thus, it can be applied or installed to any hardware capable of running Windows 10, regardless if that system uses BIOS / MBR or UEFI / GPT firmware and disk layouts.

In the following parts to this article, I will talk you through these processes (one for each item listed below):


Stay tuned for these upcoming installments, which will be labeled as listed above.



Author: Kari Finn

A former Windows Insider MVP, Kari started in computing in the mid 80’s writing code for VAX / VMS systems. Since then, he’s worked in a variety of IT positions. He specializes in Windows image capture, customization, repair and deployment as well as Hyper-V virtualization. Kari is a proud Team Member at number #1 Windows site

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