For resilience to work, all servers within the network must be part of the same domain.
For secure communication using TLS/SRTP, all IP Office systems must have an identity certificate that has been signed by the same trusted root Certificate Authority (CA).
Note:
It is important that the certificate created by a root CA has entries for DNS:<mySIPDomain>,DNS:<myFQDN.com>,IP:<IP address>, URI:sip:<IP address>, DNS:<IP address>.
You can also install Avaya root certificates on the secondary server and client computers to establish Avaya Inc. as a trusted CA.
