CARP and DHCP server

  • "CARP (Failover)" under "Status" shows that the primary box is "Master," and the backup box shows "backup."

    However, dhcpd on the primary box is disabled, and I cannot enable it. DHCP IP range on both boxes are same.

    Normally, if I configure CARP, is the primary box turn off dhcpd automatically?

  • Do you have configured the "Failover peer IP" for the DHCP server and the CARP advskew correctly on both machines?
    The DHCP service use "20" as threshold to determine whether a machine is backup or master.

  • Failover IP should be fine. I read manual, and both machines have correct IP each other. But I am not sure about advskew. I saw it in the manual, but I could not understand what to do.

    I thought I should have changed the number on these pages (attached - left is master, right is backup), but values are already there, and the left one is higher than right one.

    I attached another screen shot (service.PNG). This is what I do not understand. dhcpd on the master does not start at all.

    Could you help me to make my system work?

    Thank you.

  • Check system logs, DHCP. The errors are usually helpful. Make sure you are using the IP of the Interface you are running DHCP on as the failover peer IP. eg- on the primary (if the primary is and secondary is .3)

  • Check the DHCP Log - Do you see an error message indicating that 'dhcpd is already running' ?

    If so, remove the following file using the GUI Command Prompt:  rm /var/dhcpd/var/run/


  • Thank you very much for your help.

    Log told me some ideas. In my case, interface assignment on both devices was slightly different. After I reassigned them, it began to work.

    Thanks again!

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