KB2026.423
FAQ: SMB Dialects

This article applies to Domain Time II.

Last Updated: 23 April 2026

Beginning with version 1709 (build number 16299, Windows 10 and Server 2016), Microsoft has been step-by-step trying to eliminate the highly problematic version 1 of the Server Messaging Block protocol. SMBv1 used to be the only game in town. Windows XP and Server 2003 rely on it. Legacy SAMBA versions only support v1. Many NAS boxes and printers either rely on it or permit it.

SMBv1 is now considered obsolete due to its many flaws and security risks, including EternalBlue (MS17-010, CVE-2017-0144), WannaCry, and NotPetya. These flaws allow remote code execution (RCE), full-blown ransomware, and lateral spread of malicious code once a single machine has been breached. SMBv1 is also known as SMB 1.0 and CIFS File Sharing. It does not employ encryption or secure authentication, and can be misused to steal credentials, access supposedly locked-down documents, or even run programs with full SYSTEM privileges. See CVE-2020-1301 and CVE-2016-3345 for more details. CybelAngel has a handy write-up at SMBv1 Vulnerabilities.

Microsoft and every security firm in the world urge you to disable SMBv1 wherever possible. The newer SMBv2 and SMBv3 are much more robust and secure.

    Legacy Versions
    • Windows XP and Server 2003 cannot be upgraded to use newer SMB dialects.
    • Many SAMBA installations and printers only support SMBv1.
    • Windows Vista/2008, 2012r2, and Windows 7 through Windows 10 prior to the Fall Creators update in 2017, still install and enable SMBv1 by default, although they also support SMBv2 and/or SMBv3.

    Modern Versions
    • The first replacement for SMBv1 was SMBv2, introduced with Vista/Server 2008.
    • SMBv3 was introduced in Windows 8/Server 2012.
    • Windows 11 and Server 2022/2025 either don't install SMBv1 at all, or, if installed, have it disabled by default.

Domain Time II Manager supports remote install/upgrade/removal/control of other machines on your network. It requires valid admin credentials for the machine being contacted for operations other than basic monitoring and alerting. Manager is also able to enumerate domains and machines in Active Directory (AD) and old-fashioned Browse Lists (BL).

If you install Manager on a modern Windows OS that doesn't support SMBv1, you'll find that Workgroup discovery and enumeration of Browse Lists no longer work. There are a variety of error codes that indicate SMB dialect mismatches, everything from error 50 (request not supported) to error 64 (network name no longer available) and 1722 (RPC server not available). This is not a failure in Manager; it is the direct result of having nodes on your network that only support SMBv1 or Microsoft APIs that rely on using SMBv1, such as NetServerEnum() and WNetOpenEnum() that use the obsolete Computer Browser for enumeration. It can be difficult to know from the error code whether operations are blocked by a firewall, the Remote Registry service being disabled, the admin$ shares being removed, a segmented network, or an SMB dialect inconsistency.

Beginning in June 2026, Manager and other Domain Time components try to determine which errors are likely due to lack of SMBv1 support or are "real" networking failures. If SMBv1 is not enabled on the Manager machine and you attempt to connect to a machine that only supports SMBv1, Domain Time will examine the error code and provide a more informative error message.

In addition, if SMBv1 is not supported on your Manager machine, it will skip trying to enumerate Workgroups and Browse List members and silently fail the request instead of a long timeout before recording a possibly confusing error number and message in the logs.

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