Scenario-Based Networking Questions & Answers
1. Scenario:
A user cannot access a website, but you can ping the IP address of the server.
What could be the issue?
Answer:
- DNS resolution issue. The domain name is not translating to the IP.
- Troubleshoot with nslookup or dig to verify DNS.
- Check if the DNS server is configured correctly in the client machine.
2. Scenario:
Two hosts are in the same subnet, but they cannot ping each other.
How do you troubleshoot?
Answer:
- Check if both hosts have the correct IP & subnet mask.
- Verify ARP table – use arp -a.
- Ensure no firewall/ACL blocks ICMP.
- Check switch port status (show interface in Cisco).
- Possible VLAN mismatch between the two hosts.
3. Scenario:
You configured a static route on a router, but traffic is not flowing.
What could be wrong?
Answer:
- Check if the next-hop IP is reachable.
- Ensure the exit interface is up.
- Verify if there’s a more specific route in the routing table overriding it.
- Confirm no ACL is blocking traffic.
4. Scenario:
A server is accessible from the same LAN but not from the outside network.
What do you check?
Answer:
- Check if the default gateway is configured on server.
- Verify NAT or firewall rules on the router.
- Ensure routing is configured properly to reach external network.
- Check public IP mapping if it’s cloud/on-prem.
5. Scenario:
Your company’s web application is slow. How would you identify if it’s a network issue or server issue?
Answer:
- Use ping & traceroute to check latency/packet loss.
- Check bandwidth utilization on network devices.
- Use Wireshark/TCPdump to analyze traffic.
- If the network looks fine, check server performance (CPU, memory, application logs).
6. Scenario:
One site of your company is down, but all other sites are working fine.
How do you approach?
Answer:
- Check physical connectivity (fiber, link down, interface down).
- Verify WAN link status with ISP.
- Run routing checks (OSPF, BGP, static routes).
- Use failover/backups if HA is configured.
7. Scenario:
You see duplicate IP addresses in your network.
How do you resolve?
Answer:
- Use arp -a to identify MAC addresses.
- Locate devices with conflicting IP.
- Assign unique IP addresses or enable DHCP snooping / IP conflict detection.
- Document IP allocation properly.
8. Scenario:
A user can access websites using an IP address, but not using domain names.
What do you check?
Answer:
- Check the DNS server configuration on the client machine.
- Verify if the DNS server is reachable (ping DNS IP).
- Check if the correct DNS records are configured.
- Flush DNS cache and test again.
- Verify firewall rules allowing DNS (port 53).
9. Scenario:
Users can connect to the network but cannot access the internet.
What do you check?
Answer:
- Check default gateway configuration on client systems.
- Verify router’s internet connectivity.
- Check NAT configuration on the router/firewall.
- Confirm ISP link status and routing table.
- Check firewall rules blocking outbound traffic.
10. Scenario:
A switch port is up, but the connected device is not getting network access.
What do you check?
Answer:
- Check the VLAN configuration on the switch port.
- Verify port security settings (MAC restrictions).
- Ensure the port is not in shutdown or err-disable state.
- Check duplex and speed mismatch.
- Verify DHCP availability for that VLAN.
11. Scenario:
Intermittent network connectivity issues are reported by multiple users.
What do you check?
Answer:
- Check network congestion and bandwidth usage.
- Verify switch and router CPU/memory utilization.
- Look for duplex mismatch or faulty cables.
- Check spanning-tree loops or broadcast storms.
- Review logs for errors or interface flapping.
12. Scenario:
VPN users can connect successfully but cannot access internal resources.
What do you check?
Answer:
- Verify VPN user routing and split-tunneling settings.
- Check firewall rules between the VPN and the internal network.
- Confirm correct IP pool assignment for VPN users.
- Ensure internal routes are advertised to VPN clients.
- Check access control policies and permissions.
