Question
Thursday, May 12, 2016 12:47 PM
When defining a list of NTP servers to sync from, we can specify the following flags:
- 0x01 SpecialInterval
- 0x02 UseAsFallbackOnly
- 0x04 SymmetricActive
- 0x08 Client
Two questions here:
- Are these a bitmask i.e. can they be combined e.g. 0x9 for client mode using SpecialInterval?
- Is there documentation for exactly what each mode means? I can't find anything for the last 2 options.
All replies (7)
Wednesday, May 18, 2016 7:04 AM ✅Answered | 2 votes
Hi,
“Client/server mode is the most common Internet configuration. It operates in the classic remote-procedure-call (RPC) paradigm with stateless servers. In this mode, a client sends a request to the server and expects a reply at some future time.
Symmetric active/passive mode is intended for configurations where a group of low stratum peers operate as mutual backups for each other. Symmetric modes are most often used between two or more servers operating as a mutually redundant group. In these modes, the servers in the group members arrange the synchronization paths for maximum performance, depending on network jitter and propagation delay.”
Regarding to this question, I would suggest you take a look the following article which discussed details about client and symmetric mode, please see:
Network Time Protocol: Best Practices White Paper
http://www.cisco.com/c/en/us/support/docs/availability/high-availability/19643-ntpm.html
Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.
Regards,
Wendy
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Thursday, May 12, 2016 12:57 PM | 1 vote
Hi,
1. Yes, it can be cmbined.
2. Please find the below link for more details.
Thanks,
Arindam
Thursday, May 12, 2016 9:08 PM
Thanks. I don't see the explanation of each flag in that link though unless I'm missing something?
Thursday, May 12, 2016 10:09 PM
Hi ,
Yes you can combine the value to configure the flags which are grater tha 0x8
Below is the link for reference.
Regards,
Prathap
Monday, May 16, 2016 10:11 AM
Hi, you have answered point 1 but in the link you sent for point 2, I don't see any specific explanation for exactly what behavior each flag determines. Can you elaborate please?
Monday, May 16, 2016 1:04 PM | 1 vote
Here : https://technet.microsoft.com/en-us/library/cc779560(v=ws.10).aspx
As well,
you can combine the flags in order to deliver functionality each provides : https://social.technet.microsoft.com/Forums/en-US/ec7a74d3-6dab-42d5-94d9-399804309587/w32time-ntpserver-flag-question?forum=winserverDS
| Value | Meaning |
|---|---|
| 0x1 | Instead of following the NTP specification, wait for the interval specified in the SpecialPollInterval entry before attempting to recontact this time source. Setting this flag decreases network usage, but it also decreases accuracy. |
| 0x2 | Use this time source only as a fallback. If all time sources that are not fallbacks have failed, then the system selects one fallback time source at random and uses it. |
| 0x4 | Set the local computer to operate in symmetric active mode in the association with this source. |
| 0x8 | Set the local computer to operate in client mode in the association with this source. |
Devaraj G | Technical solution architect
Monday, May 16, 2016 1:59 PM
Thanks Devaraj G. Is there any information of what the difference between client and symmetric mode is though? the first two flags seem to indicate how to poll and the third and fourth flags seem to indicate the mode of the polling but it's not clear. For example, if the flag 0x1 is used then special polling is used but what mode is that poll?
