Windows get time from ntp server

This shows the local system time which could and in my case is wrong and how much out it is to the NTP server example above is 0. Thanks for all the responses Works fab. Thanks so much for everyone's input - and CraftyB your response is a valid answer that also works.. Sign up to join this community.

The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Asked 1 year, 5 months ago. Active 29 days ago. Viewed 4k times. Based on domain hierarchy, the Windows Time service determines the accuracy of each time server.

In a Windows Server forest, the computer that holds the primary domain controller PDC emulator operations master role, located in the forest root domain, holds the position of best time source, unless another reliable time source has been configured.

The following figure illustrates a path of time synchronization between computers in a domain hierarchy. A computer that is configured to be a reliable time source is identified as the root of the time service. The root of the time service is the authoritative server for the domain and typically is configured to retrieve time from an external NTP server or hardware device.

A time server can be configured as a reliable time source to optimize how time is transferred throughout the domain hierarchy. If a domain controller is configured to be a reliable time source, Net Logon service announces that domain controller as a reliable time source when it logs on to the network. When other domain controllers look for a time source to synchronize with, they choose a reliable source first if one is available. A cycle in the synchronization network occurs when time remains consistent between a group of domain controllers and the same time is shared between them continuously without a resynchronization with another reliable time source.

The Windows Time service's time source selection algorithm is designed to protect against these types of problems. If the computer is not a member of a domain, it must be configured to synchronize with a specified time source.

If the computer is a member server or workstation within a domain, by default, it follows the AD DS hierarchy and synchronizes its time with a domain controller in its local domain that is currently running the Windows Time service. If the computer is a domain controller, it makes up to six queries to locate another domain controller to synchronize with.

Each query is designed to identify a time source with certain attributes, such as a type of domain controller, a particular location, and whether or not it is a reliable time source. The time source must also adhere to the following constraints:. A PDC emulator can synchronize with a reliable time source in its own domain or any domain controller in the parent domain.

If the domain controller is not able to synchronize with the type of domain controller that it is querying, the query is not made. The domain controller knows which type of computer it can obtain time from before it makes the query. For example, a local PDC emulator does not attempt to query numbers three or six because a domain controller does not attempt to synchronize with itself.

The following table lists the queries that a domain controller makes to find a time source and the order in which the queries are made. A domain controller does not attempt to synchronize with itself. Each query returns a list of domain controllers that can be used as a time source.

Windows Time assigns each domain controller that is queried a score based on the reliability and location of the domain controller. The following table lists the scores assigned by Windows Time to each type of domain controller. When the Windows Time service determines that it has identified the domain controller with the best possible score, no more queries are made. The scores assigned by the time service are cumulative, which means that a PDC emulator located in the same site receives a score of nine.

If the root of the time service is not configured to synchronize with an external source, the internal hardware clock of the computer governs the time. Manually-specified synchronization enables you to designate a single peer or list of peers from which a computer obtains time. If the computer is not a member of a domain, it must be manually configured to synchronize with a specified time source.

A computer that is a member of a domain is configured by default to synchronize from the domain hierarchy, manually-specified synchronization is most useful for the forest root of the domain or for computers that are not joined to a domain. Manually specifying an external NTP server to synchronize with the authoritative computer for your domain provides reliable time.

However, configuring the authoritative computer for your domain to synchronize with a hardware clock is actually a better solution for providing the most accurate, secure time to your domain. Manually-specified time sources are not authenticated unless a specific time provider is written for them, and they are therefore vulnerable to attackers.

Also, if a computer synchronizes with a manually-specified source rather than its authenticating domain controller, the two computers might be out of synchronization, causing Kerberos authentication to fail. This might cause other actions requiring network authentication to fail, such as printing or file sharing.

If only the forest root is configured to synchronize with an external source, all other computers within the forest remain synchronized with each other, making replay attacks difficult. The "all available synchronization mechanisms" option is the most valuable synchronization method for users on a network.

This method allows synchronization with the domain hierarchy and may also provide an alternate time source if the domain hierarchy becomes unavailable, depending on the configuration. If the client is unable to synchronize time with the domain hierarchy, the time source automatically falls back to the time source specified by the NtpServer setting.

This method of synchronization is most likely to provide accurate time to clients. There are certain situations in which you will want to stop a computer from synchronizing its time. For example, if a computer attempts to synchronize from a time source on the Internet or from another site over a WAN by means of a dial-up connection, it can incur costly telephone charges. When you disable synchronization on that computer, you prevent the computer from attempting to access a time source over a dial-up connection.

You can also disable synchronization to prevent the generation of errors in the event log. Each time a computer attempts to synchronize with a time source that is unavailable, it generates an error in the Event Log.

The part about editing the Windows 10 registry to add a server to the built-in list was especially useful to me. Just want to add that the registry key change worked not only on Windows 10 but also on Windows 7 and even Windows XP. Your email address will not be published. Skip to content Advertisement.

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Copied from the request. Reciept time of the request. Send time of the response. If only a single time is needed, use this one. ReverseEndian ; orig. ReverseEndian ; rx. ReverseEndian ; tx. You can use ntohl to do the little-endian conversion, it's portable.

True, though that wouldn't solve the portability concerns about the size of unsigned int or the precise nature of the bit-field or padding. Still, probably good enough. I'm trying to resolve an issue with rec not working in another question I opened up: stackoverflow.

I need to use the ntp. So i need to apply that to my code. The problem i'm having is reading the pakket that i receive from the server. NTP usually has no preset server whatsoever, so using your belnet server should not be an issue. I still don't get it.