Before you create an xHA pair in Address Manager, make sure to
complete these prerequisites:
- You must have at least two connected and managed DNS/DHCP Servers in the configuration running software version 9.2.0 or greater.
- DNS/DHCP Servers must be either two physical appliances or two virtual machines. Mixed xHA pairs of appliance and VM are NOT supported.
- Both DNS/DHCP Servers must be at the same software version before creating an xHA pair.
- Both DNS/DHCP Servers must be configured with NTP before creating an xHA pair to ensure that the xHA setup process correctly configures the DNS/DHCP Servers.
- Both DNS/DHCP Servers must be of the same profile, such as two DNS/DHCP Server 60 or two DNS/DHCP Server 100 profiles.
- In order to create an xHA pair with the Active node on which the dedicated management interface enabled, the dedicated management interface on the Passive node must be enabled.
- The Active and Passive nodes must be on the same network.
- Additional IP addresses are not supported on DNS/DHCP Servers operating in an xHA pair.
- xHA with IPv4 only: no IPv6 addresses must be present on either the Active or Passive nodes.
- xHA with IPv6 only: no IPv4 addresses must be present on either the Active or Passive nodes.
- xHA with IPv4 and IPv6: both the Active and Passive Nodes must be configured with only one IPv4 services address and only one IPv6 services address.
- The servers for the xHA pair must not be associated with a deployment schedule. For information on viewing the servers in a deployment schedule, refer to Deployment schedules.
- The server intended for the passive role must not be associated with a deployment role. For instructions on how to view the deployment roles assigned to a server, refer to Viewing deployment roles.
- Remove any old certificates and create identical time settings on both servers.
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Attention: To avoid split-brain scenarios (where both servers are active or passive at the same time), the use of xHA Backbone Communication is mandatory.
- When configuring the xHA Backbone for DNS/DHCP Server xHA, it's important that the IP addresses of the xHA interfaces (eth1) aren't on the same subnet as the Service interface (eth0) and non-routable IP’s. For DNS/DHCP Servers with Dedicated Management enabled, the IP addresses of the xHA interface must be on a different subnet than the Management interface (by default, eth2).
- If you are currently using the xHA/eth1 ports for another purpose, you can reset and then reconfigure them for xHA communication, but you can't use the eth1 ports for xHA communication and for their previous purpose.
- If you are upgrading from an earlier version of DNS/DHCP Server software, you must delete each eth1 port to reset it. Previous versions of DNS/DHCP Server software didn't support eth1, and eth1 isn't reset automatically.
- Make sure to configure the IP address of the xHA interface (eth1) on a different subnet than any other interface. This is the recommended best practice for direct xHA Backbone connections and connections over switches or wide area networks (WAN).
Attention:
- If you are currently using the xHA/eth1 ports for another purpose, you can reset and then reconfigure them for xHA communication, but you can't use the eth1 ports for xHA communication and for their previous purpose.
- If you are running an xHA pair with xHA Backbone communication configured over switches or WAN, make sure to configure the IP address of eth1 on a different subnet than eth0 and eth2.
- If you are upgrading from a previous version of DNS/DHCP Server software that didn't support eth1, you must delete each eth1 port to reset it.
- Don't try to configure half-duplex communication. If you try to configure half-duplex, DNS/DHCP Server prevents you from saving the setting and an error message appears. For more information about duplex settings contact https://care.bluecatnetworks.com.
- You can't use xHA with Anycast; they're mutually exclusive.
- You must set the Server Identifier DHCP Service option if serving DHCP from xHA pairs configured with VLAN interfaces. For details, refer to DHCP with VLAN and xHA.