Replicating reservations necessary?

Steve 41 Reputation points
2022-08-24T22:27:31.73+00:00

We have two 2019 DHCP servers in loadbalance mode
I manually replicate a scope after creating a reservation.

BUT:

If I create a reservation on DHCP server A without manually replicating it, after some time I see the ipaddress/mac address on DHCP server B in "address Leases" as Reservation(infinite) instead of reservation(Active). Apparently this happens as soon as the affected device is online.
That IP address is no longer distributed to other devices.

If the device connects to DHCP server 2, it will get the same ip address as it is listed as Reservation(infinite) in the "address leases" folder

Questions:

  1. Is replicating reservations necessary?
  2. Is replication from Server A to Server B and vice versa?

Reagrds

Windows DHCP
Windows DHCP
Windows: A family of Microsoft operating systems that run across personal computers, tablets, laptops, phones, internet of things devices, self-contained mixed reality headsets, large collaboration screens, and other devices.DHCP: Dynamic Host Configuration Protocol (DHCP). A communications protocol that lets network administrators manage centrally and automate the assignment of Internet Protocol (IP) addresses in an organization's network.
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Accepted answer
  1. Karlie Weng 15,676 Reputation points Microsoft Vendor
    2022-08-26T07:03:30.513+00:00

    Hi @Steve

    Two DHCP servers in a failover relationship synchronize the IP address lease information on a continual basis there by keeping their respective databases up-to-date with client information and in sync with each other.

    As I understand, EVEN not manually replicate RESERVATION, the address leases folder is synced with each other. If server A goes down, printer still get the same IP from B, I think no need to manually configure reserve.

    If the scope lease time is set to an infinite lease time, the reserved client's lease is also shown as infinite.

    Best regards
    Karlie

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6 additional answers

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  1. Dave Patrick 426.3K Reputation points MVP
    2022-08-24T22:41:47.84+00:00

    Yes, you have to manually click replicate scope on the DHCP server to replicate the reservations.

    --please don't forget to upvote and Accept as answer if the reply is helpful--

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  2. Steve 41 Reputation points
    2022-08-25T10:35:22.617+00:00

    Thanks for the reply.
    I know I have to manually replicate it, and I do

    But the question is, is manual replication of the reservations necessary given that if the device in question is online, on DHCP server A de reservation is created, on DHCP server B, in address leases folder lists the device as Reservation(infinite).
    So if I wouldn't replicate manually, that's not really a problem.
    If DHCP A server goes down the device will still get de correct ip adrress after a restart from DHCP server B. Correct?

    And the other question is, is the replication bi-directional?

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  3. Dave Patrick 426.3K Reputation points MVP
    2022-08-25T15:41:02.693+00:00

    You'll only need to replicate when changes are made to configuration. You can replicate in either direction.
    https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2012-r2-and-2012/dn338989(v=ws.11)

    --please don't forget to upvote and Accept as answer if the reply is helpful--

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  4. Steve 41 Reputation points
    2022-08-25T16:59:46.807+00:00

    Hey DSPatrick,

    Thanks for your replies, but apparently you don't understand my question, or I'm doing it wrong.

    I will try again..

    The first question is specifically about reservations.
    I know I have to manually replicate a configuration change. That is obvious. I know that. That's clear..

    As I indicated in my example, I make a reservation on DHCP server A for eg a Xerox printer
    I'm NOT doing manual replication to server B

    When I turn on the Xerox printer, it is assigned the appropriate ip address specified in the reservation on DHCP server A.
    On DHCP server B there is no reservation for the Xeror printer, because I did NOT replicate it.
    But what I do see in address leases on DHCP server B, is the xerox printer`as being Reservation(infinite)
    Infinite indicates that the ip address will never be assigned to another device.

    So if DHCP server A goes down, the Xerox printer will always get the same ipaddress from DHCP server B, despite it not being mentioned in the reservations, but in the address leases in the lease expiration column as Reservation(infinite). Is this statement correct?