Network Engineer Interview Prep

Exhaustive checking of every device immediately

Blame recent changes before collecting data

Rely only on vendor-default tools without custom logs

Hypothesis-driven testing: form a theory, run targeted tests, and iterate

Use ad hoc fixes after outages rather than formal design

Maximize single-path performance to reduce cost

Avoid redundancy to prevent configuration drift

Design for graceful degradation with redundancy and clear failure modes

Customer impact (number of affected users and business criticality)

Number of devices in the entire network

Packet capture size in megabytes

Time since last firmware update

Delete all VLANs and recreate them globally

Verify native VLAN, trunk mode and allowed VLANs on both ends and check interface errors

Disable STP network-wide

Immediately replace both switch modules

Automation always creates perfect, self-explanatory configs

Documentation causes configuration drift so should be avoided

Only large teams need documentation when using automation

Automation complements but does not replace documentation because people need context, intent, and remediation steps

Only report when requested by executive leadership

Explain incident timeline, root cause, impact, corrective actions, and preventive measures concisely

Focus mainly on technical packet traces and vendor logs without business context

Delay reporting until every minor contributing factor is known

Choose the most feature-rich option without testing

Trust vendor whitepapers and accept performance numbers at face value

Rely only on sales-engineer demos under unlimited resources

Run reproducible tests in a lab that mirror production constraints and verify failure modes

Clarify assumptions, ask targeted questions, propose options with trade-offs, and state chosen assumptions

Choose the simplest option and avoid discussing trade-offs

Refuse to answer until all details are provided

Proceed with a single design without explaining assumptions