Networking is the method of interconnecting different types of hardware and software. It is thanks to networking that a Windows user can send an email to a Mac user and that a printer can printer your document without the need to copy the document manually.
Without this network interconnectivity, our gadgets can feel pretty useless. With no interaction with the outside world, your PC or laptop can’t communicate with other devices, restricting you to desktop applications. Networking issues are one of the most common root causes of technology problems and can require complex IT troubleshooting to identify the source. Before you call an IT professional, here are some simple steps to carry out yourself.
To understand how to troubleshoot networking issues, we first must understand how a network behaves. The web is built on a simple network protocol called TCP/IP. This is an open standard that is compatible with most modern hardware, and is used in private networks too (known as intranets or extranets).
The OSI model is a useful visualisation of the various layers used for networking. In order to function, each layer is dependent on the previous layer, acting as a type of pyramid.
OSI Reference Model
- Layer 1: Physical Layer
- Layer 2: Data Link Layer
- Layer 3: Network Layer
- Layer 4: Transport Layer
- Layer 5: Session Layer
- Layer 6: Presentation Layer
- Layer 7: Application Layer
All these layers are important, but there are a few layers (Physical/Network/Presentation/ Application) that can specifically help us with network troubleshooting.
Physical first: Physical Layer
Before diving into checking IP addresses and configuring applications, physically check that the devices can talk with each other! Quite often somebody has forgotten to connect a cable or the physical connection has been damaged in some way.
If it is a wireless network, you must be physically within range of the router or access pointing before the other layers can do their thing. Go back and double check wiring, and turn your router off and on again to rule any physical issues out.
IP addresses and routing next: Network Layer
Now that you are happy that the devices can physically talk to each other, you have eliminated the first factor in the troubleshooting process.
Now, check your connection settings to see if your operating system detects a network present. Even if there are other related issues, quite often the system is smart enough to detect the presence of an unusable network.
Here is how to check this in Windows:
Open Network Connections from the Start menu by clicking Control Panel, clicking Network and Internet, clicking Network and Sharing Center, and then clicking Manage network connections.
If there is no valid IP configuration, your computer does not have an identity on the network, and won’t be able to connect. An IP address is often assigned by a Dynamic Host Configuration Protocol (DHCP) controller on the network – usually a router or server. You can either send a request to the DHCP controller to get an IP address, or set your IP address manually.
If you are a OSx/MacBook user user here is comprehensive guide on How to Change Your Public & Private IP.
If it’s not the physical layer or the network layer causing issues, it’s time to move on to the presentation and application layers.
Domain Name Server (DNS): Presentation Layer
DNS translates IP addresses like 192.168.0.1 to more presentable domain names such as www.example.com. If DNS isn’t functioning correctly then you won’t be able to browse a website using the usual method of typing the address into the browser. To check if you are experiencing DNS issues try to ‘ping’ a domain name. This will essentially let you know if there is a connectivity issue or not.
If you do not receive a response to your ping then you should look at changing your DNS configuration.
Final firewalls: Application Layer
If you are able to successfully ping a domain name, then it is safe to say that your operating system has working network connectivity. If you are still experiencing issues, then it is likely that the issues reside with specific applications.
One quick check is to make sure that your firewall isn’t blocking the application as a false positive: to test this you can temporarily disable your firewall.
Alternatively, you can consult your firewall vendor’s documentation for more information on what they might be blocking and why.
- Check physical connections
- Check IP addresses/routing
- Check your DNS
- Check your Firewalls
- And if none of this is working- call in the professionals!
Joseph O’Brien is a freelance writer who has a strong interest in business, arts, and culture. You can find out more about me on my blog.