What is HA1 and HA2 in Palo Alto high availability configuration?

HA1 is the control link carrying heartbeats, hello messages, and configuration synchronization between active and passive firewalls. HA2 is the data link that synchronizes session tables, forwarding tables, IPsec security associations, and ARP entries to ensure stateful failover. HA1 uses port 28769 and 28260; HA2 uses 29281. Both require dedicated physical interfaces—typically management or dedicated data ports. Bangalore enterprises like Razorpay and Flipkart run active-passive HA pairs in their data centers. Interview tip: Explain that HA1 failure triggers split-brain scenarios, while HA2 failure causes session drops during failover because state isn't synchronized.

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