# Networking Scenario Based Questions ## Scenario One: User Cannot Access the Internet A user says they cannot access the internet but other users in the office can. How do you troubleshoot this problem. First check if the user can ping their own loopback address 127.0.0.1 to verify the network stack is working. Then check if the user has a valid IP address by running ipconfig or ifconfig. If the IP starts with 169.254 it means DHCP failed and the device assigned itself an address automatically. Check if the network cable is properly connected or if WiFi is connected. Try pinging the default gateway to check local connectivity. If that works try pinging 8.8.8.8 which is Google DNS to check internet connectivity. If pinging 8.8.8.8 works but websites do not open then the problem is DNS. Check the DNS server settings and try changing to 8.8.8.8 manually. ## Scenario Two: Network is Slow for All Users All users in an office are experiencing slow network performance. How do you diagnose and fix this. Start by checking if the problem is with the internet connection or the local network. If pinging the default gateway is fast but pinging internet addresses is slow then the problem is the internet connection or the router. Check the router CPU and memory utilization. Look for devices consuming excessive bandwidth using network monitoring tools. Check for broadcast storms by examining switch port statistics. Verify that all switch ports are running at full duplex and not half duplex. Check for any virus or malware on workstations that might be generating excessive traffic. Contact the internet service provider if the external link is the bottleneck. ## Scenario Three: Two Devices Have the Same IP Address Two devices on the network have been assigned the same IP address and both are experiencing connectivity problems. How do you resolve this. First identify which two devices have the conflicting IP. Run arp dash a on Windows or arp dash n on Linux to see the ARP table and identify MAC addresses associated with an IP. Check the DHCP server lease table to see which devices have been assigned addresses. If one device has a static IP that falls within the DHCP range, either change the static IP or configure the DHCP server to exclude that address from its pool. After resolving the conflict, release and renew the DHCP lease on the affected devices. ## Scenario Four: Cannot Connect to a Specific Website A user can access most websites but cannot access one specific website. Other users can access it fine. How do you troubleshoot. First try clearing the browser cache and cookies. Try accessing the website from a different browser. Try pinging the website domain to see if DNS resolution works. If ping fails try nslookup to check if DNS can resolve the domain. If DNS resolves but connection fails there may be a firewall rule or proxy setting blocking that specific site. Check the hosts file on the computer to see if there is an incorrect entry for that domain. Check browser proxy settings. ## Scenario Five: Network Printer Not Accessible A shared network printer was working yesterday but today no one can print to it. How do you fix this. First check if the printer is powered on and has no error lights. Check if the printer has an IP address by printing a configuration page. Try to ping the printer IP address from a workstation. If ping fails check if the network cable is connected. If the printer uses DHCP its IP address may have changed. Try connecting to the printer using its new IP. Check if the print spooler service is running on the workstations. Check if the printer driver needs to be reinstalled. Verify that no firewall rule is blocking communication to the printer. ## Scenario Six: Design a Network for a Small Office You need to design a network for a small office with 50 employees, a file server, a printer server, and internet access. Describe your design. Use a single router connected to the internet service provider to provide internet access. Connect the router to a Layer 2 managed switch. Connect all 50 workstations to the switch. Connect the file server and print server to the switch. Use the 192.168.1.0/24 address range giving 254 usable host addresses which is more than enough. Configure the router as the DHCP server to assign addresses automatically. Set up VLANs to separate workstations from servers for security. Install a firewall either as a separate device or as a feature of the router to protect the network from internet threats. Install a wireless access point connected to the switch for any wireless devices. ## Scenario Seven: Implementing VLANs in a Company A company wants to separate traffic between the IT department, HR department, and Finance department using VLANs. How do you implement this. Create three VLANs on the managed switch. Assign VLAN 10 for IT, VLAN 20 for HR, and VLAN 30 for Finance. Configure the switch ports connected to IT department computers as access ports in VLAN 10. Configure HR ports in VLAN 20 and Finance ports in VLAN 30. To allow communication between VLANs when needed, configure inter-VLAN routing using either a router with subinterfaces, called router-on-a-stick, or a Layer 3 switch. Apply access control lists to control which VLANs can communicate with each other. For example allow IT to access all VLANs but prevent HR and Finance from directly accessing each other.