Scenario: A Citrix Administrator found that whenever a NetScaler VPX high availability (HA) pair of appliances fails over, the load-balanced websites are NOT accessible. The administrator investigated the issue and found that the router and switches do NOT support gratuitous ARP (GARP). However, the administrator cannot immediately afford to upgrade the network infrastructure.
What can the administrator do immediately to resolve the issue and prevent a future outage?
Configuring a Virtual MAC (VMAC) on the NetScaler will create a floating MAC address paired with the floating IP addresses. This approach solves issues related to network devices that do not support gratuitous ARP (GARP), ensuring continuous accessibility of the load-balanced websites during a failover.
C is correct
C is correct: https://www.citrix.com/blogs/2015/01/05/netscaler-best-practice-with-vmac-in-a-high-availability-configuration/ "The NetScaler MAC addresses are not floating by default; just the IP addresses. This may cause issues with an older network switch connected to the NetScaler, or perhaps a firewall (FW) that does not understand GARP. In the event that a switch or FW does not understand GARP, or may not be able to keep up with the rate at which the GARP’s are sent during an HA failover event (approximately 200/s), the NetScaler can be configured with VMAC to create a floating MAC address to pair up with the floating IP addresses. This will solve the potential issues associated with GARP’s from the NetScaler."