In a Citrix ADC active-passive high availability pair, if the upstream router ARP table does not update after failover, which feature should be configured to resolve the issue?

In a Citrix ADC active-passive high availability pair, if the upstream router ARP table does not update after failover, which feature should be configured to resolve the issue?

• A. Route Monitor
• B. Virtual MAC
• C. HA monitor
• D. Independent Network Configuration (INC) mode

Answer: (B)

When a Citrix ADC pair is in active-passive mode, traffic for a VIP relies on a consistent MAC address that the network can route to. Virtual MAC is used to present a single MAC address for the VIP that remains owned by the active unit, even as failovers occur. If the active unit changes, the new active takes over with the same VMAC, so the upstream router’s ARP cache does not need to be updated and traffic continues flowing without interruption. This is why configuring Virtual MAC resolves a situation where the upstream router ARP table does not update after failover—the MAC address seen by the network stays constant, eliminating ARP churn. The other options don’t address MAC continuity across failover: Route Monitor concerns route health, HA monitor checks device health, and Independent Network Configuration mode changes how networks are configured, but none enforce a stable MAC for the VIP like Virtual MAC does.

When a Citrix ADC pair is in active-passive mode, traffic for a VIP relies on a consistent MAC address that the network can route to. Virtual MAC is used to present a single MAC address for the VIP that remains owned by the active unit, even as failovers occur. If the active unit changes, the new active takes over with the same VMAC, so the upstream router’s ARP cache does not need to be updated and traffic continues flowing without interruption. This is why configuring Virtual MAC resolves a situation where the upstream router ARP table does not update after failover—the MAC address seen by the network stays constant, eliminating ARP churn. The other options don’t address MAC continuity across failover: Route Monitor concerns route health, HA monitor checks device health, and Independent Network Configuration mode changes how networks are configured, but none enforce a stable MAC for the VIP like Virtual MAC does.