March 27, 2024

5 Steps to Troubleshoot your Corporate Network Issues

Computer network outages could bring numerous business processes to a halt. Here are 5 steps to streamline network outage troubleshooting to minimize the impact of business operations.

When the organization is dealing with a network outage, it is very easy to let emotions drive the troubleshooting process, attempting to quickly jump in and try different solutions in attempt to solve the problem can lead to more harm than good. The best course of action is to stay calm and determine the scope of impact. Answers such as “everything isn’t working” is not enough detail. When troubleshooting network outages, it is important to detail exactly what systems have the impact as well as the dataflow and physical network flow of the impacted systems.

The first steps should be to draw out the physical and logical flow of the impacted systems and highlight the following critical network systems as they directly impact the performance of a computer network:

  • DNS
  • Firewall (router, Gateway)
  • Switches

Once you established the scope of impact and have drawn out a physical and logical flow of the impacted systems as well as how they connect to the critical network systems (DNS, Switches and Firewall), the next step is to ensure the network connections integrity have not been compromised.

This step is critical and often overlooked. We are going to check the cables to ensure they are snug in the network socket (the network cable should not be loose on any critical network systems nor any impacted systems). If you have loose cables, the next step is to find a replacement before moving onto any other step.

Domain Naming System (DNS) takes the blame for many computer network outages. DNS translates common names such as a-mis.net to a routable IP address. Without getting too technical, every computer network (home or place of business) has a DNS for all their systems to use to find its path to the vase internet and get you the requests that you need (searching for Netflix or researching on Google).

You should first identify if DNS is at fault. Here are commands you can use to quickly identify if DNS is at fault:

Windows Operating System Commands

Nslookup {DomainName.com}

  • This command queries the DNS server, allows you to test if your DNS is functioning, if the response doesn’t resolve the domain name, then you have a DNS issue.

Ipconfig /all

  • This command displays network settings, you can find the DNS server that your computer is using by using this command.

Apple Operating System Commands

Nslookup {DomainName.com}

  • This command queries the DNS server, allows you to test if your DNS is functioning, if the response doesn’t resolve the domain name, then you have a DNS issue.

scutil –dns

  • To use this command to find your DNS server.

Linux Operating System Commands

Nslookup {DomainName.com}

  • This command queries the DNS server, allows you to test if your DNS is functioning, if the response doesn’t resolve the domain name, then you have a DNS issue.

cat /etc/resolv.conf

  • This command views the DNS configuration file in the Linux System.

Every computer network has a firewall (gateway, router, or modem), depending on your specific infrastructure configuration. Regardless of the device specifics, the basic functionality is to allow your internal computer systems to access the internet. If your firewall is not responsive (turned off) your computer systems will not be able to access the internet.

1) Your first step is to identify the IP address of your firewall, reference the following command:

Windows

  • Ipconfig: outputs your interface configuration and your firewall IP will be listed as “default gateway”.

Apple

  • route get default: outputs your interface configuration, your firewall IP will be shown as “gateway”

Linux

  • ip route: command will output default routes. You will focus on the IP address listed after “default via {IP}”.

2) The second step is to identify if you can reach your firewall.

  • Use Ping {firewall IP address}, if you get “unreachable” then your firewall is likely the problem. If you get a response from your firewall, you should ensure you are passing your firewall.

3) The Third Step is to check if your firewall is allowing your traffic pass to the internet, use the following command: tracert (windows), traceroute (non Windows Operating Systems).

Tracert/Traceroute is used to trace the path your computer takes to the internet. A response from your firewall and trace complete throughout the path means your traffic is passing through to the internet and back. No response or response from traceroute determining that your firewall is not being used means your computer isn’t passing through to the internet from your firewall.

Windows:

  • tracert {domain name}
    • Example: tracert google.com

All other OS:

  • traceroute {domain name}
    • Example: traceroute {domain name}

If you tested the firewall and confirmed all is well, your next step is the network switches.

Testing the network switches will require some technical experience.

There are three major reasons why your network outages are caused by switches:

  1. Network Loop
  2. Misconfiguration (lost configuration)
  3. Hardware Failure

Network Loop

A network loop is when your network has more than one active path carrying information from the same source to the same destination. A network loop causes degradation of network performance and at times could cause a complete outage. A common cause of a network loop is when you have two switches with more than one ethernet cable connected to each other without having Spanning Tree configured.

I would not advise you to troubleshoot any spanning tree configurations unless you are a licensed professional, however, checking for dual ethernet connections between switches is something anyone can do.

  • Walk to your network closet and any other areas that you know have network switches, checking the physical ethernet connections, note all the switches that have redundant ethernet connections. This is valuable information for your IT support staff to know when they are troubleshooting your network.

Switch Misconfiguration

A switch misconfiguration could happen if recent changes have been made in the network and something was missed. Another possible occurrence is if there was a power loss, some switches need their configurations saved manually, if they aren’t saved, after a reboot all configurations are lost.

  • If you believe there is a misconfiguration, please reach out to your IT support team or you can call us at: (725) – 272-2061

Hardware Failure

A switch hardware failure can be identified by checking the indicator lights in front of the switch chassis. If you see any red lights in front of any switch, call your I support team, or call us at: (725) – 272-2061

  • Likely will need to replace the switch or could have a component failure (depending on your switch model). Or could simply need a reboot, however, do not perform a reboot until you speak with your IT support team or calling us, rebooting a switch could fix the issue for a short period of time but will likely occur again.

A bonus tip is checking your application usage and bandwidth. This can be identified using your firewall (depending on which type of firewall you have). If your application usage is at its peak and taking up your bandwidth then you have a few options, call us for information on how to implement: (725) – 272-2061

  • Quality of Service (QoS): identifies critical applications and prioritizes them so that you can maximize your usage and ensure critical applications get the bandwidth they need.
  • Software Defined - Wide Area Network (SD-WAN): Combines bandwidth between two internet service providers to double your network bandwidth with minimal investment.

References:

Linux:

Apple Operating System Command:

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