in  MCITP 70-640 R2 Self-paced training kit , at page 593, we read : "The minimum polling interval is 15 minutes. With this setting, and using Active Directory’s default replication configuration, a change made to the directory in one site takes on average seven and a half minutes to replicate to domain controllers in another site." i don't underestand which one is true at last ? 15 min or  7.5 min ? i wonder at my exercises i noticed that replication occured between sites at about that 7.5 min  and didn't take  15 min. if that is 7.5 min , so what is the reason that they wrote 15 min ?

It should be 15 mint (inter-site), 15 seconds (intra-site).

Note that replication ocours each 15 mint but that doesn't meant that an object that was created 1 minute before replication schedule starts, in this last case the object will be replicated as soon as the replication starts.

Also note that the default can be changed to lower or higher values

Inter-site replication is 15min(KCC also runs after every 15 for intersite) where as intrasite b/w DC's is 15 sec and for notifying the replication partners it is 3 sec. 

http://technet.microsoft.com/en-us/library/cc755994%28WS.10%29.aspx

http://blogs.technet.com/b/kenstcyr/archive/2008/07/05/understanding-urgent-replication.aspx

 

Regards

Hi,

on the blog from Paul Berson you found a good explanation about the different types of replication (http://blogs.dirteam.com/blogs/paulbergson/archive/2011/04/06/active-directory-replication-types.aspx). There he wrote about the Intersite Replication:

"Intersite Replication:

DC’s between sites don’t follow the same set of rules that intrasite replication does. Changes between sites are setup on a schedule. The schedule is broken up in 15 minute increments, this schedule can also be set to only allow changes to occur at certain times of the day, thereby saving bandwidth at key points of time. The shortest time span for intersite to occur is 15 minutes and the longest is once a week. Note once replication begins between DC’s, the process will not stop until complete. So you won’t have to worry about incomplete replication activity due to time constraints."

please check also out the following links about this topic.

http://technet.microsoft.com/en-us/library/cc755994(WS.10).aspx

http://technet.microsoft.com/en-us/library/cc759160(WS.10).aspx

 

I have a Blog that can help you to understand all the different replication types at:
http://blogs.dirteam.com/blogs/paulbergson/archive/2011/04/06/active-directory-replication-types.aspx

Hopefully this can help resolve some of your confusion.

--
Paul Bergson
MVP - Directory Services
MCITP: Enterprise Administrator
MCTS, MCT, MCSE, MCSA, Security+, BS CSci
2008, Vista, 2003, 2000 (Early Achiever), NT4
http://www.pbbergs.com    Twitter @pbbergs
http://blogs.dirteam.com/blogs/paulbergson

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• Proposed as answer by i.biswajithMicrosoft community contributor Tuesday, October 11, 2011 12:23 PM
• Marked as answer by Yan Li_Microsoft contingent staff, Moderator Friday, October 14, 2011 1:51 AM

at a maximum 15 min.   the so called average is 7,5 min <----- forget this!     remember the following as your rule of thumb: the minimum interval that can be configured is 15 min and the default is 180 min (3 hours). The interval is the max amount of time that needs to pass before the DCs (between sites) initiates inbound replication. So it will take the period of the interval or less before replications starts      

<o:p></o:p>

Cheers,<o:p></o:p>

(HOPEFULLY THIS INFORMATION HELPS YOU!)
Jorge de Almeida Pinto | MVP Identity & Access - Directory Services

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"john.s2011" wrote in message news:5405db8d-e2c2-4994-9c34-29ea7fa1ae22@communitybridge.codeplex.com... in  MCITP 70-640 R2 Self-paced training kit , at page 593, we read : "The minimum polling interval is 15 minutes. With this setting, and using Active Directory??s default replication configuration, a change made to the directory in one site takes on average seven and a half minutes to replicate to domain controllers in another site." i don't underestand which one is true at last ? 15 min or  7.5 min ? i wonder at my exercises i noticed that replication occured between sites at about that 7.5 min  and didn't take  15 min. if that is 7.5 min , so what is the reason that they wrote 15 min ?

Hi,

I am agree with others, and to explan this issue, I should say that 15min is the theory replicate interval, and 7.5min is the practical relicate interval for AD information. Please refer to the thread below:

http://social.technet.microsoft.com/Forums/en-US/winserverDS/thread/ec111059-7bca-4d6f-b36e-c1bf72a5d1e7

They have the same theory.

Best Regards,

Yan Li

I??m sorry to I do not agree with that. The minimum configurable interval on a site link is 15 min. When it is configured to be 15 min, then replication may take place since the last time somewhere between 0 min (which is immediately) and 15 min. The so called calculated average is based upon the 0 min and 15 min (0 + 15 /2 = 7,5) and is pointless/meaningless value. It does not say anything concrete.  

<o:p></o:p>

Cheers,<o:p></o:p>

(HOPEFULLY THIS INFORMATION HELPS YOU!)
Jorge de Almeida Pinto | MVP Identity & Access - Directory Services

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"Yan Li_" wrote in message news:a14389e2-1716-4dbc-9d89-d5188f50901a@communitybridge.codeplex.com...

Hi,

I am agree with others, and to explan this issue, I should say that 15min is the theory replicate interval, and 7.5min is the practical relicate interval for AD information. Please refer to the thread below:

http://social.technet.microsoft.com/Forums/en-US/winserverDS/thread/ec111059-7bca-4d6f-b36e-c1bf72a5d1e7

They have the same theory.

Best Regards,

Yan Li

Hi Jorge,

I do agree with you, maybe that I am not make me clear to be understood.

This is really a issue relating calculate, the replication time is 0-15, so it is acctually 7.5min.

Best Regards,

It take 15 minutes if set at 15 minutes

run the Repadmin /showrepl

change a user profile and refresh on second site until change come through

Tested it - took 15 minutes

zero answer devided by zero answer is a zero answer to a question