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Keep shoppingNetwork Troubleshooting -75+ Real-World Incidents(CCNA-CCNP)
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259 students
Network Troubleshooting -75+ Real-World Incidents(CCNA-CCNP)
Hands-On Network Troubleshooting With Real Switching & Routing Incidents For CCNA To CCNP Level Engineers(L1, L2 and L3)
Created byCommandNet CN
Last updated 1/2026
English
What you'll learn
- Troubleshoot real-world network outages using structured troubleshooting methodology
- Identify and fix Layer 2 switching problems such as VLAN, trunking, STP, EtherChannel, and port security issues
- Diagnose interface-related problems including link up but no traffic flow, err-disabled state, and duplex mismatches
- Resolve VLAN and trunk misconfigurations that cause connectivity failures
- Analyze MAC address learning issues and MAC flapping problems
- Detect and fix switching loops and broadcast storm scenarios
- Troubleshoot STP root bridge problems and unexpected port blocking
- Understand and resolve HSRP and gateway redundancy issues
- Identify DHCP snooping and ARP inspection problems that block legitimate traffic
- Troubleshoot inter-VLAN communication failures
- Diagnose Layer 3 routing issues such as missing routes, wrong next-hop configuration, and default gateway problems
- Troubleshoot static routing and routing table update issues
- Analyze traffic flow problems even when routes are present
- Identify asymmetric routing problems and fix traffic path issues
- Troubleshoot ACL issues that block routed traffic
- Diagnose NAT failures and understand routing dependency for NAT operation
- Resolve multiple default route conflicts and route recursion issues
- Troubleshoot ARP resolution failures and proxy ARP problems
- Identify MTU mismatch and fragmentation-related packet drops
- Work with VRF-based routing issues
- Troubleshoot OSPF neighbor problems including INIT, EXSTART, LOADING, and FULL state issues
- Identify and fix OSPF area mismatch, network type mismatch, and MTU mismatch problems
- Troubleshoot OSPF route installation and LSA flooding issues
- Troubleshoot BGP neighbor connectivity and routing advertisement problems
- Identify BGP route flapping and unstable prefix issues
- Understand BGP path selection behavior and unexpected routing decisions
- Troubleshoot prefix filtering and blackhole routing problems
- Use real Cisco CLI troubleshooting commands effectively
- Perform root cause analysis instead of applying random fixes
- Build confidence to handle live network incidents in enterprise environments
- Improve problem-solving skills required for NOC and production support roles
- Prepare for CCNA and CCNP troubleshooting scenarios and job interviews
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Course content
1 section • 79 lectures • 16h 37m total length
Requirements
- Basic understanding of computer networking fundamentals
- Basic knowledge of IP addressing and subnetting
- Familiarity with VLAN concepts and switching basics
- Basic routing knowledge such as static routing and default gateway concepts
- Basic experience with Cisco CLI commands (enable, configure terminal, show commands)
- A laptop or desktop computer with internet access
- Willingness to practice troubleshooting and follow along with lab demonstrations
Description
In real production networks, configuration knowledge alone is not enough.
What truly matters is the ability to identify problems, isolate root causes, and fix network outages quickly.
This course is designed to teach you real-world network troubleshooting using 75+ practical switching and routing incidents based on Cisco enterprise environments.
Instead of only learning theory, you will work through actual network failure scenarios that engineers face in NOC, enterprise, and data center networks.
What Makes This Course Different?
Most networking courses focus on how to configure devices.
This course focuses on what to do when things break.
You will learn:
How to analyze network symptoms
How to choose the correct troubleshooting path
How to verify Layer 2 and Layer 3 issues
How to identify configuration mistakes
How to resolve incidents professionally
How to reduce downtime in real networks
Every incident is explained with:
Problem scenario
Symptoms
Verification commands
Root cause analysis
Step-by-step fix
Final validation
Switching Troubleshooting Topics Covered
You will troubleshoot real Layer 2 issues including:
Interface up but no traffic passing
Access and trunk port misconfiguration
VLAN creation and trunk allowed list problems
Native VLAN mismatch
Voice VLAN issues
MAC address learning problems
MAC flapping issues
Port security violations
BPDU Guard blocking ports
Switching loops and broadcast storms
STP root bridge and priority problems
PortFast configuration mistakes
EtherChannel formation and load balancing issues
VLAN pruning problems
HSRP misconfiguration and failover issues
DHCP snooping blocking traffic
Dynamic ARP inspection drops
Root guard blocking uplinks
ACL issues on switches
Routing Troubleshooting Topics Covered
You will also troubleshoot real Layer 3 and routing failures including:
Default gateway and static route issues
Wrong next-hop configuration
Routing table update problems
Traffic not flowing even when route exists
Asymmetric routing problems
ACL blocking routed traffic
NAT failures and routing dependency issues
Multiple default route confusion
ARP resolution failures
Proxy ARP issues
MTU mismatch and fragmentation problems
VRF misconfiguration issues
WAN link up but traffic not flowing
Backup link and failover problems
Dynamic Routing Protocol Troubleshooting
You will learn how to troubleshoot routing protocols such as:
OSPF neighbor stuck in INIT, EXSTART, and LOADING
OSPF area mismatch and network type mismatch
OSPF MTU mismatch
OSPF routes not installing
OSPF LSA flooding problems
BGP Troubleshooting Topics
Advanced routing incidents include:
BGP neighbor up but no routes
BGP prefix not advertised
BGP route flapping
BGP path selection issues
Prefix accepted but not installed
Blackhole route misconfiguration
Who This Course Is For
This course is suitable for:
L1 Network Support Engineers
L2 Network Engineers
L3 Network Engineers
NOC Engineers
Network Operations Teams
CCNA and CCNP students
System administrators working with networks
Anyone who wants to build strong troubleshooting skills
What You Will Gain From This Course
After completing this course, you will be able to:
Troubleshoot real production network issues
Handle outages with confidence
Understand traffic flow behavior clearly
Perform faster root cause analysis
Improve job performance
Prepare better for interviews
Work effectively in enterprise and ISP environments
Prerequisites
Basic understanding of:
IP addressing
VLAN concepts
Routing fundamentals
Cisco CLI basics
No advanced experience is required.
Who this course is for:
- L1 Network Support Engineers who want to build strong troubleshooting foundations
- L2 Network Engineers who want to improve problem isolation and root cause analysis skills
- L3 Network Engineers who want to sharpen advanced switching and routing troubleshooting techniques
- NOC Engineers working in monitoring and production support environments
- Network administrators managing enterprise networks
- CCNA and CCNP students who want hands-on troubleshooting experience
- IT professionals moving into networking roles
- System administrators responsible for network infrastructure
- Anyone preparing for network engineering job interviews
- Engineers who want real-world troubleshooting exposure instead of only theory
- Face real network issues and want structured troubleshooting methods
- Want to move from configuration-focused learning to problem-solving skills
- Want to handle production incidents confidently
- Want to improve your performance in NOC or enterprise support roles
- Want to gain practical experience with switching and routing failures