HTTPS would be the preferred primary connection then for Country A.  For FTP and Email you can define two different IP addresses in each.  So in theory you could have 5 different IP addresses defined in the /nas/sbin/nas_connecthome program.  So when HTTPS is failing it will fail over to either FTP or EMAIL connections.  Your thougts are correct here, set the nas_connecthome call home alerting to failover to secondary and tertiary connections when necessary.
Dear All,  I am little curious of ESRS GW cluster handling call home on specific ESRS_GW in the scenario as below : The Customer has multiple ESRS GW and joined as Cluster in service link, for example : ESRS_GW_A - Country A ESRS_GW_B - Country B ESRS_GW_C - Country C VNX device in country A is configured call home via https (primary) & Email/FTP (secondary) through ESRS_GW_A If the ESRS_GW_A was disconnected to EMC services link,there will be no call home happen on the VNX device since the ESRS_GW_A was down. is that the way to configure it failover to other ESRS_GW_B / C as call home channel?  Appreciate for Master advice.  Thank You Kian
multiple ESRS GW Cluster and VNX Call Home Configuration via HTTPS