In an HA pair, what is the purpose of configuring a VMAC address?

• A. To reduce IP address consumption.
• B. To encrypt traffic.
• C. To maintain a stable MAC address for upstream devices across failover.
• D. To enable LACP.

Answer: (C)

In an HA pair, devices upstream of the Citrix ADC rely on a known MAC address to reach the service. When you have two units, either one can be active, and without a stable MAC, the MAC that upstream devices see could shift during failover. A VMAC provides a single virtual MAC address that both nodes present to the network. This means the same MAC remains visible to switches and routers no matter which ADC is active, so the upstream CAM tables and ARP entries don’t have to be updated during failover. Traffic keeps flowing with minimal disruption because the path to the service doesn’t require re-learning at the L2 layer. This isn’t about reducing IP addresses, encryption, or link aggregation protocols like LACP. It’s about maintaining a stable L2 identity for seamless failover.