How to Troubleshoot a Network for Windows

Issues can arise at numerous points along the network. Before you start trying to troubleshoot any issue, you want to have a clear understanding of what the problem is, how it came up, who it’s affecting, and how long it’s been going on. By gathering the right information and clarifying the problem, you’ll have a much better chance of resolving the issue quickly, without wasting time trying unnecessary fixes.

I always start troubleshooting using these simple network troubleshooting steps to help diagnose and refine the issue.

• Check the hardware. When you’re beginning the troubleshooting process, check all your hardware to make sure it’s connected properly, turned on, and working. If a cord has come loose or somebody has switched off an important router, this could be the problem behind your networking issues. There’s no point in going through the process of troubleshooting network issues if all you need to do is plug a cord in. Make sure all switches are in the correct positions and haven’t been bumped accidentally.
  Next, turn the hardware off and back on again. This is the mainstay of IT troubleshooting, and while it might sound simplistic, often it really does solve the problem. Power cycling your modem, router, and PC can solve simple issues—just be sure to leave each device off for at least 60 seconds before you turn it back on. You can also ping 127.0.0.1 to check your network adapter is working or not.
• Use ipconfig. Open the command prompt and type “ipconfig” (without the quotes) into the terminal. The Default Gateway (listed last) is your router’s IP. Your computer’s IP address is the number next to “IP Address.” If your computer’s IP address starts with 169, the computer is not receiving a valid IP address. If it starts with anything other than 169, your computer is being allocated a valid IP address from your router.
• Try typing in “ipconfig /release” followed by “ipconfig /renew” to get rid of your current IP address and request a new one. This will in some cases solve the problem. If you still can’t get a valid IP from your router, try plugging your computer straight into the modem using an ethernet cable. If it works, the problem lies with the router.
• Use ping and tracert. If your router is working fine, and you have an IP address starting with something other than 169, the problem’s most likely located between your router and the internet. At this point, it’s time to use the ping tool. Try sending a ping to a well-known, large server, such as Google, to see if it can connect with your router. You can ping Google DNS servers by opening the command prompt and typing “ping 8.8.8.8”; you can also add “-t” to the end (ping 8.8.8.8 -t) to get it to keep pinging the servers while you troubleshoot. If the pings fail to send, the command prompt will return basic information about the issue.
  You can use the tracert command to do the same thing, by typing “tracert 8.8.8.8”; this will show you each step, or “hop,” between your router and the Google DNS servers. You can see where along the pathway the error is arising. If the error comes up early along the pathway, the issue is more likely somewhere in your local network.
• Perform a DNS check. Use the command “nslookup” to determine whether there’s a problem with the server you’re trying to connect to. If you perform a DNS check on, for example, google.com and receive results such as “Timed Out,” “Server Failure,” “Refused,” “No Response from Server,” or “Network Is Unreachable,” it may indicate the problem originates in the DNS server for your destination. (You can also use nslookup to check your own DNS server.)
• Contact the ISP. If all of the above turn up no problems, try contacting your internet service provider to see if they’re having issues. You can also look up outage maps and related information on a smartphone to see if others in your area are having the same problem.
• Check on virus and malware protection. Next, make sure your virus and malware tools are running correctly, and they haven’t flagged anything that could be affecting part of your network and stopping it from functioning.
• Review database logs. Review all your database logs to make sure the databases are functioning as expected. If your network is working but your database is full or malfunctioning, it could be causing problems that flow on and affect your network performance.