DHCP Failover- how does the replication work?

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DHCP Failover- how does the replication work?

Eduard Martinenko 111

I have configured DHCP Failover between my two windows servers, that are also domains controllers (the first windows server 2012 and the second one is windows server 2016)
So I have some questions about automatic replication
When you first enabled the DHCP Failover feature all options from this pool are copied on the second server.
But what about the future edits? Will they be copied from the one server to the second?
Or do I have to manually click the synchronize button every time I make any changes to the zone?
How are the conflicts resolved?

Gloria Gu 3,941 Reputation points

2020-08-25T06:11:44.933+00:00

Hi,
Just checking in to see if the information provided was helpful. Please let us know if you would like further assistance.

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Gloria Gu 3,941 Reputation points

2020-08-25T06:11:44.933+00:00

Hi,
Just checking in to see if the information provided was helpful. Please let us know if you would like further assistance.

Answer 1

Hi,

In regards to your issue, here're my suggestions:

When you first enabled the DHCP Failover on the specific scope, all features from this pool are copied on the second server. It includes lease information and scope options.
After my test in the environment, if the client leases are updated in one server, the lease information will be automatically copied to the parterner server.

However, if the scope options are changed, it will not automatically synchronize，you have to mannually configure Scope replication. This type of replication copies the configuration of a selected DHCP scope to the failover partner server.

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Regards
Gloria

Answer 2

TimCerling(ret) 1,156

After you have established which hosts are partners in DHCP failover, updates are automatically replicated. It is not necessary to manually synchronize unless you find some sort of disparity that needs your attention, but generally you will not see any difference between hosts.

Answer 3

Eduard Martinenko 111

Do the IP reservations get copied automatically?
What is the difference between "Replicate scope" and "Replicate relationship"?

Gloria Gu 3,941 Reputation points

2020-08-24T01:34:03.663+00:00
Hi,

Yes, IP reservations get copied automatically.

2.Relationship replication: This type of replication copies the configuration of all DHCP scopes that are part of a selected failover relationship to the failover partner server.
Scope replication: This type of replication copies the configuration of a selected DHCP scope to the failover partner server.
For more details please refer to :
dn338989(v=ws.11)

-------If my answer is helpful to you, please remember to mark them as answer. Thank you!------
Joe Spears 6 Reputation points

2021-04-06T18:58:43.543+00:00

In case someone else finds this same doc, note that "Yes, IP reservations get copied automatically." is a typo.

IP/DHCP LEASES are automatically copied. DHCP RESERVATIONS are not.

I came here looking for someone to say they're copied automatically, but my testing shows they're not and there's lots of other documentation and blog type stuff online that says they're not.
Rob Nicholson 66 Reputation points

2021-10-09T10:06:53.757+00:00

This is indeed correct and still the case with Windows Server 2019. You can schedule the following PowerShell command to replicate the scope automatically:

Invoke-DhcpServerv4FailoverReplication -Force
Gabriel Luiz 41 Reputation points MVP

2022-02-21T18:25:35.957+00:00

Is there any difference in DHCP failover function in Windows Server 2012 R2, Windows Server 2016, 2019 and 2022?

Are scopes automatically replicated in Windows Server 2012 R2, including reservations created?
Gabriel Luiz 41 Reputation points MVP

2022-02-21T18:29:59.657+00:00

Post the documentation link that informs that the reversals are replicated, please.
Joe Spears 6 Reputation points

2022-02-21T20:03:43.267+00:00

I ended up implementing about 50 scopes across two Server 2019 DHCP servers in a large environment. I saw that DHCP reservations EVENTUALLY replicate but could not tell how long that would take, so I left screenshots for the technicians to replicate the scopes after a change (same as GloriaGu's screenshot). I did not have to script anything.

The DHCP failover has been working well. There was one systemic difference on every scope, where on the first server we had it set to automatically update DNS records on behalf of clients, but on the replica on the other server that option was unchecked. We manually matched them up one time.

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DHCP Failover- how does the replication work?

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