Networking troubleshooting
✅ What is Networking Troubleshooting?
Network troubleshooting is the process of identifying, diagnosing, and resolving problems in a computer network — including internet connection issues, device communication failures, slow speeds, and more.
👉 Goal: Make sure devices can communicate smoothly, access the internet, and share resources.
🔑 Common Network Problems:
No Internet Access
"Can't connect to Wi-Fi."
Slow Network Speed
Websites take long to load.
IP Address Conflicts
Two devices have same IP.
DNS Issues
"Server not found" errors.
Hardware Failures
Broken router or switch.
Wi-Fi Dead Zones
No signal in parts of home.
Limited Connectivity
Connected but "No internet."
Firewall/Port Block
App can't connect online.
🛠️ Basic Network Troubleshooting Steps:
1. Check Physical Connections
Ensure cables are connected properly.
Make sure router/modem are powered on.
Look for blinking lights on routers (power, internet, Wi-Fi).
2. Restart Devices
Restart computer, router, modem.
Fixes many temporary issues (clears memory, re-establish connections).
3. Check IP Configuration
Use command:
Windows:
ipconfig /allLinux/Mac:
ifconfigorip addr
Verify correct IP address, subnet mask, and default gateway.
🔄 Renew IP:
Windows:
ipconfig /releaseand thenipconfig /renew.
4. Ping Test (Check Connectivity)
Check if you can reach local devices or external servers.
Examples:
ping 192.168.1.1(router)ping 8.8.8.8(Google DNS)
Good ping: Shows response time (e.g.,
Reply from 8.8.8.8: bytes=32 time=12ms).Bad ping: "Request timed out" or "Destination host unreachable."
5. DNS Check
If websites won't load but ping works:
DNS may be broken.
Test DNS:
nslookup google.com— should return IP address.
Try changing to public DNS:
Google DNS:
8.8.8.8,8.8.4.4.Cloudflare DNS:
1.1.1.1.
6. Traceroute (Check Path to Server)
Command:
Windows:
tracert google.comLinux/Mac:
traceroute google.com
Shows path and where connection may be failing.
7. Check Router & Modem Status
Log into router's web interface:
Usually:
192.168.1.1or192.168.0.1.
Check WAN (Internet) status.
Reboot from settings if needed.
8. Wi-Fi Issues?
Ensure correct SSID & password.
Check for interference (microwave, cordless phones).
Switch to 5GHz band if supported (less crowded).
Check signal strength — move closer to router.
9. Check Firewalls & Security Software
Sometimes firewall/antivirus blocks network traffic.
Temporarily disable firewall and test connection.
Check router firewall settings.
10. Hardware Fault Check
Test connection with a different device (phone, laptop).
If others work, issue is on the first device.
Swap cables, check ports, try another router if possible.
💻 Essential Network Troubleshooting Tools:
ping
Test connection to device/server.
tracert/traceroute
Show path to remote server.
ipconfig/ifconfig
Show IP configuration.
nslookup/dig
Test DNS resolution.
netstat
Show active connections.
pathping
Diagnose packet loss on path.
arp -a
View ARP table (device IP to MAC mapping).
🚦 Flow Chart Example for Troubleshooting "No Internet":
yamlCopyEditStart
|
v
Are cables connected? -- No --> Fix cables
|
Yes
|
Reboot router/modem -- Still no internet? -- Yes --> Call ISP
|
No
|
Check IP config --> Is IP assigned? -- No --> Renew IP
|
Yes
|
Ping router --> Success? -- No --> Check router settings
|
Yes
|
Ping 8.8.8.8 --> Success? -- No --> ISP issue or DNS issue
|
Yes
|
DNS resolution (nslookup) --> Fails? --> Change DNS
|
End🧠 Common Network Commands Recap:
ping
Test reachability of host.
tracert / traceroute
Trace route to host.
ipconfig / ifconfig
Show IP info.
netstat
Show network connections.
nslookup
DNS testing.
arp -a
ARP cache table.
🔑 Final Tips:
Start simple: Check cables and restart.
Test in steps: Local, gateway, public IP.
Document steps for future reference.
Use multiple tools for a full picture.
Keep firmware updated (routers, switches).
Secure network with strong passwords & firewall.
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