CCNA Troubleshooting: 7 Real Network Issues You Must Know

Theory alone is not enough.
Real skills come when things break.

These are real problems every network technician faces.

❌ 1. Interface down

Problem

Cannot reach a device.

Check

show ip interface brief

Causes

• unplugged cable
• shutdown port
• device off

❌ 2. Ping fails

Problem

Ping does not respond.

Check

ping 192.168.1.1traceroute 192.168.1.1

Causes

• wrong gateway
• firewall
• missing routing

❌ 3. Duplex mismatch

Problem

Slow or unstable connection.

Check

show interfaces

Causes

• mismatched duplex settings

❌ 4. DHCP failure

Problem

No IP assigned.

Check

• DHCP enabled?
• correct VLAN?

Causes

• unreachable DHCP server
• misconfiguration

❌ 5. DNS issues

Problem

Hostnames do not resolve.

Check

ping google.comping 8.8.8.8

Causes

• DNS not configured
• DNS unreachable

❌ 6. VLAN misconfiguration

Problem

Devices cannot communicate.

Causes

• different VLANs
• trunk issues

❌ 7. Routing issue

Problem

Networks cannot reach each other.

Check

show ip route

Causes

• missing routes
• incorrect configuration

🎯 Conclusion

Troubleshooting is learned by doing, not just reading.

🔗 Learn more

https://www.certifyquiz.com/certifications/ccna
https://www.certifyquiz.com/certifications/ccna/technical-support