Settings for minimizing periodic WAN traffic
This article provides some suggested settings for the problem that occurs when a dial-on-demand link is activated by periodic WAN traffic.
Applies to: Windows Server 2016, Windows Server 2012 R2, Windows 10 - all editions
Original KB number: 819108
This article describes the registry settings and the Group Policy settings that affect periodic wide area network (WAN) traffic and metered link costs. If you have a dial-on-demand link, it might be unexpectedly enabled by periodic WAN traffic. You can configure the system's components and services to minimize periodic WAN traffic and to reduce metered link costs.
Your dial-on-demand link activates while the computer is idle if the following conditions are true:
- You are using a Microsoft Windows-based computer that's connected to a remote network and is a member of an Active Directory Domain Services (AD DS) domain.
- You are connected to the domain controllers over a dial-on-demand or otherwise metered link.
The following sections contain a comprehensive summary of registry settings and Group Policy settings that you can add or modify to minimize WAN traffic. Some of these settings depend on the operating system version that the computer is running.
Part 1: A description of relevant settings
The following registry settings affect WAN traffic and metered-link costs. To minimize periodic WAN traffic and to reduce metered link costs, configure these settings as appropriate.
The Browser service
In Windows Server 2016, Windows 10, and later versions, the Browser service is generally no longer used. We recommend that you disable the service on all computers in your enterprise, if it is possible. If you can't do this, we recommend you turn down the communication intervals of the service.
The domain master browser periodicity
The primary domain controller (PDC) is always the domain master browser. Therefore, a master browser on a network that does not host the PDC for the domain activates dial-on-demand links when it tries to locate the PDC. By default, the attempt interval is five minutes. You can create a MasterPeriodicity registry entry that instructs the Browser service to adjust its default interval for contacting a domain master browser. By default, the MasterPeriodicity entry is not present. The recommended default for dial-on-demand deployments is 86,400 seconds (one day).
Recommended value (seconds): 86,400
Server list maintenance
If you enable a server to participate as a browser and to potentially be elected as a master browser for its network, the server periodically contacts the PDC for its domain. By default, the MaintainServerList registry entry is set to Auto. The recommended value is No unless you must have browser functionality on the network. If you must have browser functionality, set this value to Yes. However, make sure to configure the MasterPeriodicity interval to a large enough interval to reduce the number of PDC contacts.
Type: String Default value: Auto
Recommended value: No
The expected dial-up delay
The ExpectedDialupDelay entry specifies the time that is required for a dial-up router to dial when it sends a message from a client computer to a domain across a slow link. In this scenario, the domain is trusted by the client computer. Typically, the Net Logon service assumes that it can quickly reach a domain controller. By setting the ExpectedDialupDelay entry, you inform the Net Logon service to expect an additional delay. The recommended value for this setting is the average time in seconds that is required for the dial-on-demand link to be established, plus a constant of five seconds to account for variance.
Recommended value (seconds): 90
The AvoidPdcOnWan entry
The AvoidPdcOnWan entry instructs the domain controller that is running the Net Logon service to avoid contacting the PDC operations master roles as much as it can. (The operations master roles are also known as flexible single master operations roles or FSMO roles.) The AvoidPdcOnWan entry also instructs other components, such as the Security Account Manager (SAM), that use this information. For example, assume that this entry is enabled on a domain controller in a remote site. In this scenario, the remote domain controller will not try to verify a password with the PDC operations master roles if the client does not authenticate with the local domain controller.
Recommended value: 1 (enabled)
Directory service client queries
In Windows 2000 Service Pack 2 and in later Windows 2000 service packs, in Windows XP, and in Windows Server 2003, the Directory service client queries are issued one time per hour. You can adjust the following registry entries to extend this query time beyond one hour.
The negative cache period
The NegativeCachePeriod entry specifies the time that a client will remember that a domain controller could not be found in a domain. If a program tries again within this time, the client call immediately fails without trying to find a domain controller again, so the metered link is not activated.
Default value (seconds): 45
Recommended value: 84,600
The background retry initial period
Some programs periodically try to find a domain controller. If the domain controller is not available, these periodic retries can be costly in dial-on-demand scenarios. The BackgroundRetryInitialPeriod entry defines the minimum amount of elapsed time before the first retry occurs. If the value is smaller than the value set in the NegativeCachePeriod entry, the NegativeCachePeriod value is used.
Recommended value (seconds): 84,600
The background retry back-off period
The BackgroundRetryMaximumPeriod entry defines the maximum interval that the retries will be backed off. For example, if the first retry is after 10 minutes, the second retry will be after 20 minutes, and the next retry will be after 30 minutes. This continues until the value in the BackgroundRetryMaximumPeriod entry is reached. Then, the BackgroundRetryBackoffPeriod value is used for the retry interval until the value in the BackgroundRetryQuitTime entry is reached.
Recommended value (seconds): 84,600 seconds
The background retry quit time
When a program runs a periodic search for domain controllers and cannot find a domain controller, the value that is set in this entry determines when retries are no longer possible.
Recommended value (seconds): 600
The maximum password age
Specifies how frequently the system changes the computer account password of the local computer. This entry is used only when the system is configured to change the computer password automatically at set intervals. That is, this entry is used only when the value of the DisablePasswordChange entry is 0. For more information, see Domain member: Disable machine account password changes.
Default value (decimal, number of days): 7 (in Windows NT), 30 (Windows 2000/XP/2003) Recommended range: 42 to 70
DFS registry settings
The frequency of domain controller queries by DFS the DfsDcNameDelay entry can reduce the frequency of domain controller queries by Distributed File System (DFS). Modify this entry on the client computer.
Default value (minutes): 15
The valid range for DfsDcNameDelay is from 15 to 360 minutes. No restart is required for the new settings to take effect.
The frequency of PDC queries by DFS
Description: Every DFS server that has a domain-based DFS root polls the PDC for changes on the root object. You can control the interval between pollings by setting the SyncIntervalInSeconds registry entry on the DFS root server or servers. By setting this entry, you can control when DFS returns referrals that are based on cached data. If you increase this value, DFS caches namespaces and referrals for a longer duration.
Default value (seconds): 3,600 (1 hour)
Also review the following Microsoft Docs topic on DFS volume settings: Change the amount of time that clients cache referrals
The Knowledge Consistency Checker (KCC) replication topology update
The Knowledge Consistency Checker (KCC) replication topology update may cause WAN traffic to create or verify replication links. For domain controllers that are separated by metered links, it makes sense to reduce the frequency at which KCC runs.
Description: The Repl topology update period (secs) value defines the number of seconds between intervals.
Entry: Repl topology update period (secs)
Default value (seconds): 900 (15 minutes)
Group Policy settings
The following policy settings control the frequency of Net Logon-based traffic and of DFS-based traffic. To locate these settings, click Start, click Run, type gpedit.msc, and then click OK. Or, edit them in a domain-based Group Policy Object.
Computer Configuration/Administrative Templates/System/Net Logon
- Scavenge Interval
- Positive Periodic DC Cache Refresh for Non-Background Callers
- Positive Periodic DC Cache Refresh for Background Callers
- Final DC Discovery Retry Settings for Background Callers
- Maximum DC Discovery Retry Interval Settings for Background Callers
- Initial DC Discovery Retry Settings for Background Callers
- Negative DC Discovery Cache Settings
- Contact PDC on logon failure
- Expected dial-up delay on logon
Computer Configuration/Administrative Templates/Network
Sets how often a DFS Client discovers DCs
By default, a DFS client tries to discover domain controllers every 15 minutes. If you enable the Sets how often a DFS Client discovers DCs setting, you can change the interval. This value is specified in minutes. If you disable this setting or do not configure it, the default value of 15 minutes applies. The corresponding registry subkey is as follows:
Part 2: Default values
Default values for packet types
The following table shows the packet types and their default send intervals.
|NetLogon||Server message block (SMB)||TCP/IP||300 seconds|
|KeepAlive||Network basic input/output system (NetBIOS)||TCP/IP||3,600 seconds (60 minutes)|
|Echo NetBIOS over TCP/IP (NetBT)||NetBIOS||TCP/IP||120 seconds||If a session is idle, the file server sends an SMB echo frame at the specified interval.|
|Windows Explorer||SMB||TCP/IP||32 seconds||This value controls the frequency that the file server sends an SMB echo frame to the client as long as the client has an outstanding long-term request open.|
|KeepAlive||NetBIOS||TCP/IP||300 seconds (5 minutes)||This entry corresponds to
|KeepAlive||TCP||TCP/IP||1 second||This entry corresponds to
- The Browse packet type in this table indicates network traffic between a PDC (Domain Master Browser) and master browsers.
- The Windows LAN Manager redirector echoes an SMB echo frame every 30 seconds or 32 seconds to each file server that has an associated long-term request that is outstanding. For example, a file server might have a NotifyChange request in Microsoft Internet Explorer. To avoid these packets, you can set the NoRemoteChangeNotify key.
For more information, see the following Knowledge Base article: 3212430 Security setting changes on folders don't appear immediately on DFSR replication partners in Windows Server
If there is no data transfer between the client and the server for the KeepAlive interval (120 seconds), the server sends the first keep-alive probe. After two minutes of inactivity (idle tree connects), the file server sends a 1-byte session message. The TCP payload is "02." The TCP sequence number starts in the last received acknowledgment (ACK) minus 1 and ends in the current acknowledgment.
If the connection against the server is made by using named pipes, the server sends a "NetBT: SS - Session Keep Alive" message to the client approximately every 300 seconds.
The "NetBT SessionKeepAlive" entry is in the following registry subkey:
A Common Internet File System (CIFS) TCP session keep-alive message includes a byte that has a 0x85 value, followed by three bytes that have a 0 (zero) value in the NetBT header. The keep-alive message may be sent if no messages have been sent for a client-configurable interval.
Default values for services
|Component||Default interval setting||Notes|
|The Net Logon domain controller discovery||3,600 seconds (60 minutes)|
|DFS queries for domain controllers||900 seconds (15 minutes)|
|GPO refresh interval||90 minutes||See Group Policy Description: Group Policy Search|
|Time service (W32time)||17 minutes||This value is found in the following registry subkeys:
Also see the Group Policy settings for Windows Time Service: Global Configuration Settings Configure Windows NTP Client
For more information, see the following Knowledge Base articles: