IP Address & Hostname Failover Matrix (EXPRESSCLUSTER × Azure / AWS)

Item	Azure	AWS
Virtual IP (VIP) failover	❌ Not supported (VIP not available)	✅ Supported (via ENI reattachment)
Elastic IP reassignment	❌ Not applicable (no EIP concept in Azure)	✅ Supported (reassign EIP to new instance)
Secondary IP failover	❌ Not recommended (NIC manipulation limited)	✅ Supported (multiple IPs on ENI)
DNS hostname switching	✅ Supported (Azure DNS + script automation)	✅ Supported (Route 53 + script automation)
Virtual Computer Name (vcom)	⚠️ Limited (NetBIOS constraints)	⚠️ Limited (not recommended in cloud)
Dynamic DNS resource (ddns)	✅ Recommended (cloud-friendly)	✅ Recommended (cloud-friendly)

Notes

• Azure does not support Layer 3 VIP failover, so DNS-based switching is the mainstream approach.
• AWS offers more flexibility with ENI and EIP, enabling direct IP failover.
• vcom (Virtual Computer Name) is designed for on-premises use; DNS-based alternatives are preferred in cloud environments.
• Script resources can be used to automate DNS or IP updates during failover events.