replication time for dynamic records from primary to secondary servers

[Cuttler, Brian R (HEALTH) via bind-users]

Sorry, crisis (not named related)

I will post sections of the named.conf later if needed, but will answer the simple questions now.

I don't know what the propagation delay is, notifications are enabled, when the primary reloads a zone the secondary gets notified and requests a zone xfer.
When the secondary expires a zone a zone xfer request is sent to the primary.

I suspect that is happening is that when DHCPd creates/expires dynamic records in the primary we are not notifying the secondary of the change and there is no Ixfer.
That it what I was looking for and don't know where to find it, but looks to me like the button I want to press.
Is that where I should be looking?

Thanks,
Brian

-----Original Message-----
From: bind-users <bind-users-***@lists.isc.org> On Behalf Of John Thurston
Sent: Tuesday, March 30, 2021 5:00 PM
To: bind-***@lists.isc.org
Subject: Re: replication time for dynamic records from primary to secondary servers

ATTENTION: This email came from an external source. Do not open attachments or click on links from unknown senders or unexpected emails.

We are seeing a delay in the primary DNS server updating the secondary and would like to shorten that interval.

Can you post the pertinent bits of your primary's and secondary's config
for the zone?

In the absence of that, I pose a few questions:

How long is it taking now?
What is your target interval?

Do you have NOTIFY enabled on the primary?
How large is the zone?
If you look in the log, do you see XFRs queuing?
How many secondaries are there?
Do you have limits defined on the number of simultaneous transfers?

--
Do things because you should, not just because you can.

John Thurston 907-465-8591
***@alaska.gov
Department of Administration
State of Alaska
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[S***@registry.godaddy]

We are seeing a delay in the primary DNS server updating the secondary and would like to shorten that interval.

Can you post the pertinent bits of your primary's and secondary's config
for the zone?

In the absence of that, I pose a few questions:

How long is it taking now?
What is your target interval?

Do you have NOTIFY enabled on the primary?
How large is the zone?
If you look in the log, do you see XFRs queuing?
How many secondaries are there?
Do you have limits defined on the number of simultaneous transfers?

Additional question, do you have "notify-delay" defined?

Stuart

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[Tony Finch]

We are seeing a delay in the primary DNS server updating the secondary
and would like to shorten that interval.

This is probably due to NOTIFY messages not working. NOTIFY is the
mechanism that allows primary servers to tell secondaries to get the
latest version of a zone promptly. I wrote some notes on debugging slow
zone transfers a couple of weeks ago:

https://lists.isc.org/pipermail/bind-users/2021-March/104278.html

Tony.
--
f.anthony.n.finch <***@dotat.at> https://dotat.at/
Fair Isle: North 5 or 6, decreasing 3 or 4, then backing northwest 4
or 5 later. Moderate or rough, becoming slight or moderate. Mainly
fair. Good.

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[Cuttler, Brian R (HEALTH) via bind-users]

Tony,

I don't think the issue I'm having is related to notify message not being reacted to nor zone transfer requests not being sent to answered.

What I think I'm seeing is DHCP updating the DNS primary, which works correctly, but I don't believe it updates the SOA serial number nor sends a notify message.

When you add a record to a zone, either by # nsupdate or via the transaction (I assume nsupdate protocol) between DHCP and DNS primary does something else need to be configured in order to get that incremental change sent to the secondary? Something that does not normally need to be set?

The issue is not that frequently noticed. The typical problem that crossed by desk looks like this.
- Someone put a new printer online, it gets an IP from DHCP and asks DHCP to register its "name" with DNS which DHCP does on behalf of our printers
and desktop computers (we do not allow the end points to create DHCP records).
- I don't believe this updates the SOA serial number nor generates a Notify message, thought at could be a deficiency in the config.
- At some point the secondary gets all of the updated records from the primary but in that interval the print server is updated to create a new print
queue and if it queries the DNS secondary the printer name may fail to resolve.

The answers we have employed are 1) be patient 2) remove the deficient zones files from the DNS secondary and restart the DNS secondary.

Should the incremental update from the DHCP server cause DNS to update the SN and send a notify message?
Is there some other mechanism to update the secondary?

Thanks,
Brian

-----Original Message-----
From: Tony Finch <***@hermes.cam.ac.uk> On Behalf Of Tony Finch
Sent: Wednesday, March 31, 2021 11:43 AM
To: Cuttler, Brian R (HEALTH) <***@health.ny.gov>
Cc: bind-***@lists.isc.org
Subject: Re: replication time for dynamic records from primary to secondary servers

ATTENTION: This email came from an external source. Do not open attachments or click on links from unknown senders or unexpected emails.

We are seeing a delay in the primary DNS server updating the secondary
and would like to shorten that interval.

This is probably due to NOTIFY messages not working. NOTIFY is the
mechanism that allows primary servers to tell secondaries to get the
latest version of a zone promptly. I wrote some notes on debugging slow
zone transfers a couple of weeks ago:

https://protect2.fireeye.com/v1/url?k=9a160f3f-c58d367e-9a14f60a-000babda0106-d930663ddef913a2&q=1&e=067dcc81-1082-4e21-a672-c998f736beca&u=https%3A%2F%2Flists.isc.org%2Fpipermail%2Fbind-users%2F2021-March%2F104278.html

Tony.
--
f.anthony.n.finch <***@dotat.at> https://protect2.fireeye.com/v1/url?k=4efddec9-1166e788-4eff27fc-000babda0106-90e4f91c3445cf30&q=1&e=067dcc81-1082-4e21-a672-c998f736beca&u=https%3A%2F%2Fdotat.at%2F
Fair Isle: North 5 or 6, decreasing 3 or 4, then backing northwest 4
or 5 later. Moderate or rough, becoming slight or moderate. Mainly
fair. Good.

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[Tony Finch]

Post by Cuttler, Brian R (HEALTH) via bind-users
I don't think the issue I'm having is related to notify message not
being reacted to nor zone transfer requests not being sent to answered.

It's worth checking the logs to make sure that they agree with what you
expect.

Post by Cuttler, Brian R (HEALTH) via bind-users
What I think I'm seeing is DHCP updating the DNS primary, which works
correctly, but I don't believe it updates the SOA serial number nor
sends a notify message.

The server is required (by RFC 2136 section 3.6) to update the serial
number after an UPDATE. I would not expect any delay unless the server is
in the middle of a lot of updates and has reached a notify or transfer
rate limit - the logs should tell you if that has happened, or if there
are any ACL-related problems.

Tony.
--
f.anthony.n.finch <***@dotat.at> https://dotat.at/
Gibraltar Point to North Foreland: Northeasterly backing northwesterly
3 or 4, occasionally 5 at first, backing southwesterly 4 to 6 later.
Slight or moderate, becoming mainly slight. Fair. Good.


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[Bob McDonald]

Is there an entry in your server options similar to this?

notify-delay nn;

Regards,

Bob