Network Engineer Pre-Employment Quiz: Assess Your Technical Expertise

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| By Anam Khan
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Anam Khan
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Quizzes Created: 96 | Total Attempts: 5,548
| Attempts: 11
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  • 1/10 Questions

    Your coworker misconfigured a router, now no devices can reach the web

    • IP was assigned statically
    • DNS server is unreachable
    • Default gateway is missing
    • Firewall blocked outgoing traffic
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About This Quiz

Ever been that person in a job interview who nailed the resume but blanked when asked about subnetting? Or stared at a topology map like it was an alien language? You're not alone. Many aspiring tech professionals feel confident—until they're faced with a network engineer pre employment test that digs deep into routing protocols, firewall rules, and DNS troubleshooting.

This quiz is your chance to simulate the pressure before it hits for real. We've structured each question to reflect what real-world recruiters expect you to know—covering everything from packet flow logic to network security layers. If you're preparing for your first job or just brushing up, this test can help highlight what you know—and what you need to sharpen.

Network Engineer Pre-employment Quiz: Assess Your Technical Expertise - Quiz

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  • 2. 

    Your laptop connects to Wi-Fi but shows “No Internet”

    • DHCP lease expired

    • DNS cache is corrupted

    • Incorrect subnet mask

    • Captive portal not completed

    Correct Answer
    A. DHCP lease expired
    Explanation
    A Wi-Fi connection showing “No Internet” often points to DHCP issues. When a lease expires and isn’t renewed, devices keep a local IP or fall back to an APIPA address (169.x.x.x), leading to connection without true access. DNS cache and subnet mask issues typically cause resolution or routing errors, but wouldn’t fully cut off internet access. A captive portal can cause delays, but usually redirects rather than outright blocks connectivity. Therefore, a DHCP lease expiration is the most common culprit.

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  • 3. 

    You're setting up VLANs, but devices can’t talk across them

    • Switch doesn’t support VLANs

    • Trunk port not configured

    • VLANs use dynamic routing

    • DNS entries not updated

    Correct Answer
    A. Trunk port not configured
    Explanation
    When VLANs can't communicate, it’s often because the trunk port between switches or routers isn’t correctly set up. A trunk port allows tagged traffic from multiple VLANs to traverse a single link, which is critical for inter-VLAN routing. If it’s not configured, the VLANs are isolated, even if routing exists elsewhere. Unsupported switches or DNS have no bearing here. Dynamic routing doesn’t apply unless already enabled between VLANs, and even then, without a trunk, it’s useless. So, trunk misconfiguration is the root issue.

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  • 4. 

    A ping to 8.8.8.8 returns "Destination Host Unreachable"

    • Wrong static route configured

    • ICMP disabled on destination

    • Local interface down

    • NAT misconfiguration

    Correct Answer
    A. Local interface down
    Explanation
    Destination Host Unreachable is a local device error, meaning it cannot find a route to the destination. The most probable reason is that the local interface is down or misconfigured. Unlike a “Request Timed Out” error which suggests a remote issue, this one suggests something wrong with the source. ICMP or NAT issues can affect ping responses but wouldn’t throw this specific error. Similarly, a wrong route could cause misdirection but not this host-level failure. Hence, the correct issue lies with the local network interface.

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  • 5. 

    You see duplicate IP warnings in your logs

    • ARP table is full

    • DHCP server is assigning overlaps

    • Two devices set same static IP

    • IPv6 has conflict with IPv4

    Correct Answer
    A. Two devices set same static IP
    Explanation
    Duplicate IP errors usually arise when two machines have the same static IP, causing ARP conflicts. DHCP typically avoids this unless misconfigured, and full ARP tables wouldn’t show this specific error. IPv6 doesn't conflict with IPv4 since they operate on separate stacks. Manual static settings being duplicated—often by mistake or poor documentation—is the most common scenario leading to this log alert. That’s why this answer stands out as the most accurate.

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  • 6. 

    DNS queries from clients are taking forever

    • DNS recursion disabled

    • Firewall blocks DNS port

    • DNS server overloaded

    • TTL on packets too low

    Correct Answer
    A. DNS server overloaded
    Explanation
    DNS queries being delayed or timing out commonly point to server overload. When the server can’t handle the request volume or has high CPU/memory usage, response times suffer. DNS recursion, port blocking, or TTL settings would result in different failure symptoms—like immediate failure or limited resolution. Slow performance almost always means the DNS server is operational but overwhelmed. This makes “DNS server overloaded” the clearest and most direct root cause for the slowdown.

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  • 7. 

    Your router config is wiped after every reboot

    • Flash memory is corrupted

    • Config not saved to startup

    • Router is out of storage

    • Device has a firmware virus

    Correct Answer
    A. Config not saved to startup
    Explanation
    When a router loses configuration after reboot, it’s typically because the changes weren’t saved to startup config. In most devices (like Cisco), you must manually write the running configuration to non-volatile memory. Otherwise, it reverts to its previous saved state. Flash corruption or firmware issues would manifest differently—like complete boot failure or erratic behavior. Forgetting to save changes is a simple but frequent human error, and it matches the issue described exactly.

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  • 8. 

    Colleague asks why traceroute fails after 3 hops

    • Packet loss too high

    • DNS resolution failed

    • ICMP blocked on intermediate

    • TTL is set to max

    Correct Answer
    A. ICMP blocked on intermediate
    Explanation
    A traceroute failing after three hops often points to ICMP being blocked beyond a certain network boundary. Traceroute works by sending packets with gradually increasing TTL values, expecting ICMP time-exceeded responses. If an intermediate router or firewall is configured to ignore these, the path goes dark. DNS failure would block resolution entirely, not just partial hops. Packet loss would make the trace intermittent, not consistently cut off. Thus, ICMP blocking is the logical explanation.

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  • 9. 

    Remote access VPN connects, but user can’t reach internal resources

    • Split tunneling misconfigured

    • Subnet mask too broad

    • Port forwarding not enabled

    • DNS records expired

    Correct Answer
    A. Split tunneling misconfigured
    Explanation
    When a VPN connects but internal resources are unreachable, split tunneling is the usual suspect. If split tunneling is misconfigured, the traffic meant for internal IPs may be routed through the public internet instead, causing the internal servers to appear unreachable. Subnet or DNS issues may play a role but wouldn't affect a working tunnel’s routing logic. Port forwarding applies more to NAT, not remote internal access. So, the routing misdirection caused by poor split tunneling setup is the real issue.

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  • 10. 

    After switching to a new switch, no hosts are getting IP addresses

    • DHCP relay not configured

    • Broadcast domain is saturated

    • Default gateway changed

    • ARP protocol is disabled

    Correct Answer
    A. DHCP relay not configured
    Explanation
    When switching to a new switch and DHCP fails across devices, the absence of DHCP relay configuration is most often the cause. In multi-subnet or VLAN environments, DHCP relays forward client requests to the DHCP server. Without it, broadcasts don’t reach the server, and clients get no IP. Broadcast saturation, gateway changes, or ARP settings wouldn’t cause full DHCP failure across the board. DHCP relay being overlooked in reconfiguration is a critical but common oversight.

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  • Current Version
  • Jun 09, 2025
    Quiz Edited by
    ProProfs Editorial Team
  • May 29, 2025
    Quiz Created by
    Anam Khan
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