The foundation nobody talks about
Before you open Palo Alto. Before you touch a single policy.
- #engineer-series
- #paloaltonetworks
- #networkengineering
- #cybersecurity
- #firewallengineer
By Mrugesh Patel, Senior Network Security Engineer
Originally posted on LinkedIn — Engineer Series · 2026-05-04
Before you open Palo Alto. Before you touch a single policy.
A firewall is a network device first. A security device second.
I’ve worked with engineers who knew every Palo Alto feature by heart. But couldn’t explain why traffic wasn’t reaching the firewall in the first place.
That wasn’t a policy problem. That was a routing problem.
Here’s what you must understand before firewall ever makes sense:
✅ How a packet actually travels through a network
✅ What a routing table decides — and why
✅ What VLANs are and how they segment traffic
✅ How ARP works at Layer 2 before Layer 3
✅ Why a wrong default gateway means your firewall sees nothing
➡️ Lab it in GNS3, EVE-NG, or Packet Tracer
➡️ Get routing and switching fundamentals solid
➡️ Then every firewall concept will click
Palo Alto, Fortinet, Checkpoint — doesn’t matter. They all sit inside a network. And that network will humble you if you ignore it.
What networking concept do you wish someone told you to learn first?
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