Zones — the concept that breaks every junior engineer
The single concept that breaks every junior Palo Alto engineer.
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By Mrugesh Patel, Senior Network Security Engineer
Originally posted on LinkedIn — Engineer Series · 2026-05-25
The single concept that breaks every junior Palo Alto engineer.
Zones.
Not interfaces. Not subnets. Zones.
If you came from Cisco ASA or another traditional firewall, this trips you up immediately. Because zones aren’t just labels — they’re the foundation of every policy decision Palo Alto makes.
Here’s what new engineers consistently get wrong:
❌ Thinking a zone equals an interface
→ One zone can hold many interfaces. Many zones can sit on one VLAN trunk.
❌ Building rules with “any” source/destination zone
→ That defeats the entire model. You’re back to port-based thinking.
❌ Forgetting intrazone traffic
→ Traffic within the same zone is allowed by default. Surprise.
❌ Mixing trust levels in one zone
→ Your DMZ and internal users in the same zone? You just removed the wall.
The shift that changes everything:
➡️ Group interfaces by trust level — not by physical location
➡️ Name zones by function (untrust, dmz, users, servers, mgmt)
➡️ Every rule should be zone-to-zone, explicitly
➡️ Enable intrazone logging — you will be surprised
When you finally “get” zones, the rest of Palo Alto stops feeling random.
What’s the worst zone misconfiguration you’ve ever inherited?
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