Objective

Document production helpdesk troubleshooting scenarios for Windows, networking, Linux, and user support ; demonstrating the diagnostic methodology, root cause analysis, and remediation process used in enterprise IT environments.

Environment: Simulated multi-user production environment | Windows 10/11, Active Directory, ServiceNow

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Scenario 1: User Cannot Access the Internet

Symptoms

• User reports browser shows "No Internet" or pages fail to load
• Other users on the same network are unaffected
• Device shows network connection as "Connected"

Tools Used

• ipconfig : check IP address, subnet mask, default gateway, DNS
• ping : test connectivity to gateway and external hosts (8.8.8.8)
• nslookup : verify DNS resolution is working
• traceroute / tracert : identify where packets are dropping
• Windows Network Settings / Network Troubleshooter

Troubleshooting Steps

1. Run ipconfig /all : confirm device has a valid IP (not 169.254.x.x APIPA)
2. Run ping 127.0.0.1 : verify local TCP/IP stack is functional
3. Run ping <default gateway> : test connectivity to router
4. Run ping 8.8.8.8 : test external IP connectivity (bypasses DNS)
5. Run nslookup google.com : test DNS resolution
6. If DNS fails, set DNS manually to 8.8.8.8 or 1.1.1.1 to isolate the issue
7. Run ipconfig /release then ipconfig /renew to refresh DHCP lease
8. Run netsh winsock reset if all above pass but browser still fails
9. Check if issue is browser-specific (try different browser or incognito)
10. Escalate to network team if gateway is unreachable

Root Cause Analysis

Problem: User unable to access the internet despite showing as "Connected."

Investigation:

• Verified physical connectivity : cable seated, switch port active
• Ran ipconfig /all : device showed APIPA address (169.254.x.x), confirming no valid DHCP lease
• Pinged gateway — timed out, confirming network layer failure
• Confirmed DHCP server was temporarily unreachable during lease renewal window

Root Cause: Expired DHCP lease resulted in automatic APIPA self-assignment (169.254.x.x), preventing all network communication.

Resolution: Ran ipconfig /release and ipconfig /renew. Device obtained valid IP from DHCP server. Internet access restored immediately.

Preventive Action: Documented DHCP lease duration settings and verified DHCP scope had sufficient available addresses. Logged incident and resolution in ServiceNow.

Business Impact

Additional DNS Observation

During testing, ICMP connectivity to external IP addresses was successful using:

ping 8.8.8.8

However, DNS resolution testing with:

nslookup google.com

returned:

*** Unknown can't find google.com: No response from server

Analysis

This indicates that basic network connectivity was functional, but DNS name resolution experienced issues communicating with the configured DNS server.

Troubleshooting Performed

• Verified IPv4 connectivity
• Reviewed configured DNS servers using ipconfig /all
• Tested external connectivity with ICMP
• Confirmed issue was isolated to DNS resolution

Lesson Learned

Successful network connectivity does not always guarantee successful DNS resolution. Troubleshooting should isolate connectivity issues from name resolution failures.

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Scenario 2: User Cannot Access Shared Network Folder

Symptoms

• User receives "Network path not found" or "Access denied" when accessing shared drive
• Other users on the same team can access the folder without issues
• User was able to access it previously

Tools Used

• ping : verify network connectivity to file server
• nslookup : confirm DNS resolution of server hostname
• Windows Credential Manager : check stored credentials
• Active Directory Users and Computers : verify group membership and permissions
• Event Viewer : check for authentication or access errors
• net use : view and manage mapped network drives

Troubleshooting Steps

1. Confirm the shared path is correct : ask user for exact path they are using
2. Run ping <server hostname> : verify network connectivity to file server
3. Run nslookup <server hostname> : confirm DNS is resolving correctly
4. Try accessing the share via IP address instead of hostname — isolates DNS vs. access issue
5. Check Windows Credential Manager — remove stale/cached credentials for the server
6. Verify user is still a member of the correct AD security group (Active Directory Users and Computers)
7. Check share permissions AND NTFS permissions — both must allow access
8. Check Event Viewer on the server for Event ID 5140 (share access) or 4625 (failed logon)
9. Re-map the drive using net use or Group Policy if permissions are confirmed correct
10. Escalate to sysadmin if NTFS/share permissions require changes beyond helpdesk scope

Root Cause Analysis

Problem: User received "Access Denied" on a previously accessible shared network folder.

Investigation:

• Pinged file server : successful, confirmed network connectivity intact
• Attempted access via IP : same "Access Denied" error, ruled out DNS issue
• Checked Active Directory : user had been removed from the FinanceTeam security group during a routine quarterly access review
• Confirmed share and NTFS permissions were correctly configured for the group

Root Cause: User was inadvertently removed from the Active Directory security group controlling access to the shared folder during a quarterly access review process.

Resolution: Re-added user to the FinanceTeam AD security group. User logged off and back on to refresh group membership token. Share access restored within 5 minutes.

Preventive Action: Flagged access review process for improvement ; recommended a verification step before removing users from production groups. Documented in ServiceNow and escalated recommendation to IT manager.

Business Impact

Loss of access to shared financial documents prevented the user from completing time-sensitive reporting tasks. Swift resolution within SLA avoided escalation to management. Process improvement recommendation submitted to reduce recurrence risk across the team.

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Additional scenarios in progress: Password Reset & Account Lockout | Slow PC Performance | Printer Not Found | VPN Connectivity Failure