FLINT HILLS TECHNICAL COLLEGE
Network Troubleshooting Flowchart

START
Windows Workstation Unable to Access a Network Service
Gather Clues
A. Ask Questions.
 i. What were you doing when the problem occurred?
ii. Have there been any recent changes to the network?
B. Have the customer recreate the problem while you watch.
While watching, check for obvious user errors (ID10T errors), such as Caps-Lock being on.
Do other workstations on the LAN have the same problem?
Yes  or  No
↓        
Are the switch, hub, or wireless access point's power & link-lights lit?
Yes  or  No
↓        
ping the destination by name. Successful?
Yes  or  No
        ↓
ping the destination by IP address. Successful?
Yes  or  No
        ↓
Execute: ipconfig /all
on at least two LAN workstations having the same problem. What type of IP addresses?
DHCP starting with 169.254 (APIPA)  or  DHCP IP addresses  or  Static IP addresses
                        ↓
ping Default Gateway router. Successful?
Yes  or  No
↓        
On which LAN is the destination located?
Same LAN as workstation.  or  Different LAN on the Internet.  or  Different LAN, but still on this organization's network.
↓                                                                                                                                     
Possible Solutions
A. Destination down or locked-up. Boot or reboot it. Plug it in first if it is unplugged from power.
B. Bad cable or cable unplugged between destination and switch/hub. If the link-lights are not lit on the destination, this is probably the problem.
C. Misconfigured IP settings on destination. Check its IP settings and correct them if necessary.
D. DHCP server is giving out wrong subnet mask. Properly configure DHCP server’s scope to provide correct subnet mask.
E. Destination’s firewall software is blocking access. Try disabling firewall software on destination. If it fixes problem, reconfigure firewall software to allow access to your LAN.
F. Faulty, disabled, or misconfigured NIC on destination. Verify NIC is enabled and has correct drivers installed. Verify that it is configured for correct speed. Test with loopback or swap with another NIC to see if it is bad.
G. Malware infection on destination server or it has been hacked. Scan server for malware infection using anti-malware software such as MalwareBytes. Check for signs of break-in (look at the logs).
If All Else Fails
A. Sniff the network with Wireshark on the destination while recreating the problem. See if packets are actually arriving at destination. Look for packets containing diagnostic or error messages.
Problem Solved?
Document Your Solution
FINISHED

Click here for a graphical version of this flowchart.