Why pre-screen network engineers before the technical interview
Almost every serious network outage follows a change somebody made. The engineers worth hiring plan changes with a rollback, make them in a window, and can describe the one that went wrong anyway and how they recovered. A short screen asks about a change that caused an outage, which surfaces both technical depth and honesty in one answer.
What actually matters when screening Network Engineer candidates
- 01
Technical depth
Check depth on BGP and OSPF behaviour, VLAN and VXLAN design, MPLS, QoS policy, and firewall rulesets; ask which vendor CLIs (Cisco IOS-XE, Juniper Junos, Arista EOS) they run daily.
- 02
Work that shipped
Probe concrete builds: datacentre spine-leaf migrations, SD-WAN rollouts, campus refreshes, IPv6 addressing plans. Ask for site counts, circuit types, cutover windows and measured downtime.
- 03
Diagnosis under uncertainty
Test troubleshooting of intermittent faults: asymmetric routing, duplex mismatches, spanning-tree loops, DHCP scope exhaustion. Ask how they use packet captures, SNMP or NetFlow, and syslog correlation.
- 04
Working across the org
Assess how they coordinate with security, server, and application teams during change windows; look for CAB approvals, documented runbooks, and handling carrier or ISP escalations.
Pre-screening questions to ask Network Engineer candidates
12 questions grouped by what they test. Ask the same set in every screen and score answers on a consistent scale, or send them as an async video screen and compare answers side by side.
Networks they built
3 questions01Can you describe the largest network you have been responsible for?
Listen forSite and user counts with their actual responsibilities, including change and incident ownership.
Scale claimed without detail, or responsibility limited to executing instructions.
02Can you describe your experience with network engineering?
Listen forDesign, build and operate experience, with the technologies they are strongest in named honestly.
Experience described broadly, or design work that was always done by somebody else.
03How have you improved a network in a previous role?
Listen forA specific improvement with the measurement behind it, in resilience, performance or cost.
Improvements described as upgrades installed, or benefits never measured afterwards.
Genuine protocol depth
4 questions04Can you describe your experience with core network services and protocols?
Listen forName resolution, addressing and remote access understood well enough to debug them from packets.
Services described at product level, or protocol behaviour never examined in a capture.
05Can you explain the differences between the current address protocol versions?
Listen forReal understanding of addressing and transition mechanisms, backed by practical deployment experience.
The newer protocol known in theory only, or differences described as address length alone.
06How familiar are you with cloud networking environments?
Listen forVirtual networking and the connectivity to on-premises infrastructure both handled in practice.
Cloud networking assumed identical to physical, or hybrid connectivity never configured.
07Do you have experience with wireless network technology?
Listen forCoverage and capacity designed from surveys, with interference and client behaviour understood.
Wireless problems solved by adding access points, or surveys never conducted.
Security designed in
3 questions08Have you set up and managed a firewall, and how did you approach it?
Listen forRules built from understood traffic flows, with regular review to remove what is no longer needed.
Rules only ever added, or broad permissive rules left in place to resolve a problem quickly.
09Do you have experience implementing network security controls?
Listen forSegmentation and access control implemented in phases, with traffic analysed before enforcement.
Controls applied without understanding existing flows, or segmentation never attempted.
10How would you handle a situation where network data was compromised?
Listen forContainment first with evidence preserved, and the security team engaged rather than working alone.
Devices reconfigured before evidence is captured, or an incident handled without escalation.
Diagnoses methodically
2 questions11Can you describe a challenging network problem you solved?
Listen forA difficult fault isolated with captures and logs, with the reasoning described step by step.
Problems solved by replacing hardware, or the cause never confirmed after the symptom stopped.
12Do you have experience managing vendors and service contracts?
Listen forProvider performance held to the contract, with faults escalated using evidence they gathered.
Provider explanations accepted without evidence, or service credits never pursued.
How to score responses
Score every candidate on the same four criteria immediately after the screen. At this stage you are shortlisting for panel interviews, not making the final call.
Technical depth
35%5Explains route reflectors, BFD timers and MTU or MSS pitfalls precisely, and names certifications such as CCNP or JNCIP with real config experience.
Work that shipped
30%5Describes a named cutover with scope, maintenance window, rollback plan and post-change latency or packet loss figures they personally owned.
Diagnosis under uncertainty
20%5Walks a specific outage from alert to root cause using Wireshark traces or interface counters, and names the permanent fix, not just the restart.
Working across the org
15%5Cites change tickets, vendor TAC cases pushed to resolution, and clear diagrams or IPAM records that let others operate the network unaided.
Almost every serious outage follows a change somebody made. A one-way video screen asks about theirs.
Try it on HirevireScreening FAQ
Process basics
How long should a pre-screening round for this role take?
Fifteen minutes across eight to ten questions, answered async. Enough to establish networks they built, test their protocol depth, and check security and diagnostic method.
How does this differ from a performance engineer screen?
Performance work focuses on diagnosis and optimisation of an existing network. This role designs and builds, so weight architecture, security and change management more heavily.
Evaluating answers
What is the strongest signal when screening this role?
A change that caused an outage. Engineers with real responsibility have one and describe the recovery and the process change afterwards. Anyone with a spotless record has made few changes.
How do I judge their security thinking?
Ask how they would segment a flat network. Real answers cover phased implementation and traffic analysis first. Anyone who proposes rules without understanding existing flows will break things.
Go deeper on this role
Sanat has been hiring since 2012 and watching the recruitment industry change up close ever since, and turned that screening process into Hirevire's video screening platform. LinkedIn
