For a decade, the primary client component of the service was the Windows Update web app that could only be run on Internet Explorer.

Arie Slob, writing for the Windows-help.net newsletter in March 2003, noted that the size of the update list had exceeded 400 KB, which caused delays of more than a minute for dial-up users.

The tool queries the Microsoft server for a file called "cucif.cab", which contained a list of all the critical updates released for the operating system.

Once the check is executed, any custom schedule defined by the user is reverted to the default.

Microsoft stated that this ensures that users receive notification of critical updates in a timely manner.

[12] An analysis done by security researcher H. D. Moore in early 1999 was critical of this approach, describing it as "horribly inefficient" and susceptible to attacks.

The scope of this attack is big enough to attract crackers who actually know what they are doing..."[13] Microsoft continued to promote the tool through 1999 and the first half of 2000.

After Windows Me is installed, a notification balloon prompts the user to configure the Automatic Updates client.

Automatic Updates in Windows XP gained notoriety for repeatedly interrupting the user while working on their computer.

"[14] In 2013, it was observed that shortly after the startup process, Automatic Updates (wuauclt.exe) and Service Host (svchost.exe) in Windows XP would claim 100% of a computer's CPU capacity for extended periods of time (between ten minutes to two hours), making affected computers unusable.

The cause was an exponential algorithm in the evaluation of superseded updates, which had grown large over the decade following the release of Windows XP.

The revised dialog box that prompts for the restart appears under other windows, instead of on top of them.

This feature helps Windows recover cleanly in the event of an unexpected failure, as file changes are committed atomically.

All updates, regardless of type (this includes hardware drivers), are downloaded and installed automatically, and users are only given the option to choose whether their system would reboot automatically to install updates when the system is inactive or be notified to schedule a reboot.

[23][24] Microsoft offers a diagnostic tool that can be used to hide troublesome device drivers and prevent them from being reinstalled, but only after they had already been installed and then uninstalled without rebooting the system.

his can cause confusion for administrators who do not comprehend the full ramifications of the dual scan mode.

[36] As organizations continued to use more computers, the per-machine Windows Update clients started to become unwieldy and insufficient.

A component of the Windows Server family of operating systems, WSUS downloads updates for Microsoft products to a server computer on which it is running and redistributes them to the computers within the organization over a local area network (LAN).

One of the benefits of this method is a reduction in the consumption of Internet bandwidth, equal to (N-1)×S, where N is the number of computers in the organization and S is the size made by the updates.

In case of the latter, Microsoft deployment utilities such as DISM, WADK and MDT can consume these packages.

Microsoft offers System Center Configuration Manager for very complex deployment and servicing scenarios.

The product integrates with all of the aforesaid tools (WSUS, DISM, WADK, MDT) to automate the process.

A number of tools have been created by independent software vendors which provide the ability for Windows updates to be automatically downloaded for, or added to, an online or offline system.

One common use for offline updates is to ensure a system is fully patched against security vulnerabilities before being connected to the Internet or another network.

A second use is that downloads can be very large, but may be dependent on a slow or unreliable network connection, or the same updates may be needed for more than one machine.

On Patch Tuesday, the day Microsoft typically releases new software updates, outbound traffic could exceed 500 gigabits per second.

[46] Initially, Microsoft was very vague about specific changes within each cumulative update package.

[48] On the same day ,SHA-1 updates were discontinued for older Windows versions prior to 7 and Server 2008.

It also offers Silverlight and Windows Media Player as optional downloads if applicable to the operating system.