7 Appendix B: Product Behavior

  • Article

The information in this specification is applicable to the following Microsoft products or supplemental software. References to product versions include updates to those products.

  • Windows Vista operating system

  • Windows Server 2008 operating system

  • Windows 7 operating system

  • Windows Server 2008 R2 operating system

  • Windows 8 operating system

  • Windows Server 2012 operating system

  • Windows 8.1 operating system

  • Windows Server 2012 R2 operating system

  • Windows 10 operating system

  • Windows Server 2016 operating system

  • Windows Server operating system

  • Windows Server 2019 operating system

  • Windows Server 2022 operating system

  • Windows 11 operating system

  • Windows Server 2025 operating system

Exceptions, if any, are noted in this section. If an update version, service pack or Knowledge Base (KB) number appears with a product name, the behavior changed in that update. The new behavior also applies to subsequent updates unless otherwise specified. If a product edition appears with the product version, behavior is different in that product edition.

Unless otherwise specified, any statement of optional behavior in this specification that is prescribed using the terms "SHOULD" or "SHOULD NOT" implies product behavior in accordance with the SHOULD or SHOULD NOT prescription. Unless otherwise specified, the term "MAY" implies that the product does not follow the prescription.

<1> Section 2.1: In Windows Vista and Windows Server 2008, support for the client-side elements of this protocol is available only with the optional installation of the Background Intelligent Transfer Service (BITS) [MC-BUP] via the Windows Management Framework (WMF). Support for the server-side elements of this protocol is not available for Windows Vista or Windows Server 2008. For more information, see [MSDN-BITS].

<2> Section 2.2.2: Version 2.0 of the Content Information structure is not supported by Windows 7 and Windows Server 2008 R2.

<3> Section 2.2.3.4: Windows generates a new GUID for the URI when the service starts.

<4> Section 2.2.3.5: MetadataVersion MUST be set to 1 for Windows Vista, Windows Server 2008, Windows 7, and Windows Server 2008 R2.

<5> Section 2.2.3.5: MetadataVersion MUST be set to 2 for Windows, except for Windows Vista, Windows Server 2008, Windows 7, and Windows Server 2008 R2.

<6> Section 2.2.3.6: In Windows 7 and Windows Server 2008 R2 operating system, the InstanceId is generated by taking the boot time of the service in seconds since 1970-01-01 Time 00:00:00 UTC.

<7> Section 3.2.2: In Windows 7 and Windows Server 2008 R2, the default value for the request timer is 300 milliseconds, and the default maximum backoff timer value on the server peer is 65 milliseconds. However, these two values are configurable in Windows 7 and Windows Server 2008 R2 and can be set by system administrators based on the specific network environment.

<8> Section 3.2.4.1: In Windows 7 and Windows Server 2008 R2, the following rules are used to determine whether a server peer will reply to a Probe message when it has the requested segment.

When the server peer first requests and downloads a segment as a client, it records the number of replies it receives and whether the replies contain the entire segment or just a portion of the segment. Later, when the server peer receives a Probe message for that segment, it proceeds as follows (where n is an administratively configurable parameter with the default value n = 10):

  • If there were fewer than n replies, the server peer will respond to the new Probe after the backoff timer expires.

  • If there were at least n replies:

    • If there were at least n full-segment replies, the server peer will not reply to the new Probe.

    • If there were fewer than n full-segment replies, the server peer will randomly determine whether to reply to the new Probe, with a probability of 0.33 for replying.