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katredrumFlag for United States of America

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Windows 2003 DNS Server Cross Site Transfer Time

Hello Experts,

I have two sites in a Windows 2003 domain. I blacked out the interval time that AD syncs during normal business hours. Since DNS also syncs at the same interval, if a RR changes or updates or if I add a forward zone, what will the interval be for the sync to happen?

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Brian Pierce
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Not sure what you are asking as you seem to have answered your own question - DNS will replicate with AD replication - assuming that its AD integrated DNS
It depends on the zone type, if its an AD integrated, then:

1. DCs in the same site will replicate changes each 15 minuets.
2. DC cross sites will replicate changes each 3 hours.

above are the default values.
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I apologize for not being clearer. The picture shows my AD intervals that is configured to not sync during business hours. But when there is an update during business hours each DC in each site does sync and I just wanted to know what that interval is or when to expect it.

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I'm talking about DNS to DNS server in both sites.
Each site have one DC called bridge head DC, its responsible for the sync between its own site the other sites and then it syncs the traffic inside its site normally ( each 15 min).

Per your attached schedule, sync will occur (once per hour) and only in the active area ( non bussness hoers).

again it depends on the zone type.
You can add zones and do the changes in DNS. but, it will replicate to other DNS servers after and before the business hours. As you scheduled in replication.

We seem to be going round in circles. with AD integrated DNS then DNS is replicated at the same time as DNS, using the same protocol - is one and the same thing. Either I'm misreading the question or you are misinterpreting the answer - I'm not sure which?
I understand that AD integrated DNS replicates the same schedule as AD (between sites) is set to so I think we're on the same page there. Although I've configured AD (and DNS) to replicate after hours, when I add a forward zone in one office, it does however replicate during business hours. This also goes for adding a host record, when I add a host entry in DNS it eventually transfers over to the other site.

So going back to the question, I was wondering what the replication interval was for when it transfers outside the regular schedule transfers.
"Determining when intersite replication occurs

Active Directory preserves bandwidth between sites by minimizing the frequency of replication and by allowing you to schedule the availability of site links for replication. By default, intersite replication across each site link occurs every 180 minutes (3 hours). You can adjust this frequency to match your specific needs. Be aware that increasing this frequency increases the amount of bandwidth used by replication. In addition, you can schedule the availability of site links for use by replication. By default, a site link is available to carry replication traffic 24 hours a day, 7 days a week. You can limit this schedule to specific days of the week and times of day. You can, for example, schedule intersite replication so that it only occurs after normal business hours. For more information, see Configure site link replication frequency and Configure site link replication availability."

Source :
The default interval for cross-site replication is 3hrs - 180mins (+/-) - it can be changed.

Within a site its 5 mins
for a detailed explanation of how replcation works see
sorry - just realised that that link has already been posted
So the inter-site replication is 5 minutes outside the regular scheduled AD replication?
By default 5 mins WITHIN the same site
180 mins BETWEEN sites
nope, intersite replication is 3 hours; intersite means replication across sites.

for intrasite ( inside the same site) the replication is 15 min
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Brian Pierce
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Any update here ?
KCTS has the best answer but still no one can point to an exact reference or duration Windows takes to update. For example, I added a CNAME record on one DC...the DC in the same site receives the update in about 5 minutes or less. The remote site however, it receives it during the non-scheduled time but I don't know what the duration is. I tried to time it but it took too long and gave up. It could be 15-30 minutes would be my guess but I'd like an explanation on how Windows decides i.e. too much congestion, will try again or sync DNS later (will try again in 5 min).