Q: Explain the difference between SNAT and DNAT.
Network Address Translation alters IP headers as packets transit a router/firewall.
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🎙️ Candidate Opening & Architectural Context
""When an interviewer asks how I diagnose network connectivity, I follow an outside-in OSI model approach. The interviewer is testing: IP tables, Network Address Translation concepts.. I structure my answer around systematic triage first, root cause analysis second, and permanent remediation third.""
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🛠️ Production Runbook & Step-by-Step Resolution
1️⃣
Initial Diagnostics & Root Cause Analysis
Network Address Translation alters IP headers as packets transit a router/firewall.
- SNAT (Source NAT): Translates the *Source* IP address. Used when internal private IPs need to reach the internet. The router (like an AWS NAT Gateway) changes the private source IP to its own public IP so the return traffic knows where to go back. (Usually happens Post-Routing).
- DNAT (Destination NAT): Translates the *Destination* IP address. Used for port forwarding. If an external user hits your router's public IP on port 80, the router changes the destination IP to an internal private server's IP. (Usually happens Pre-Routing).
2️⃣
Remediation & Permanent Safeguards
💡 The Senior SRE Gold Nugget (Key Architectural Takeaway)
"Pro-Tip: SNAT (Source NAT): Translates the *Source* IP address. Used when internal private IPs need to reach the internet. The router (like."
⚡ 60-Second Elevator Pitch Talking Points
- SNAT (Source NAT): Translates the *Source* IP address. Used when internal private IPs need to rea...
- DNAT (Destination NAT): Translates the *Destination* IP address. Used for port forwarding. If an ...
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