Curriculum topic
Troubleshooting
FullA structured method for isolating a fault, and reading the shape of a problem from the symptoms it produces.
- lesson
- 6 lessons
- quiz
- 10 quizzes
- question
- 20 questions
- lab
- 24 labs
Taught, assessed and practised in a lab.
Why this matters
Network+ weights troubleshooting more heavily than any other domain, and it is the one skill that does not transfer from reading alone - it needs a broken network to practise on.
Further reading
Technical guides
Learn
Modules covering this topic
6 lessons on this topic, sequenced inside these modules alongside their quizzes and labs.
- Diagnosis in practiceNetwork operations and design
- Direction and stateNetwork security and acls
- Filtering by addressNetwork security and acls
- Dhcp in operationNetwork services
- Services assessmentNetwork services
- Network basicsNetworking fundamentals
- Network servicesNetworking fundamentals
- Switching and vlansNetworking fundamentals
- BgpRouting protocols
- Choosing a pathRouting protocols
- EigrpRouting protocols
- Knowing what is plugged inRouting protocols
- Ospf areas and faultsRouting protocols
- Static routing faultsRouting protocols
- When the link is the problemRouting protocols
Practice
Hands-on labs
Real virtual networks with device consoles, graded automatically. Addressing is regenerated on every attempt.
- Egress Filter on the Records Server
- The Firewall That Never Saw the Request
- Traffic Leaves by the Backup Circuit
- eBGP Session Up, No Routes
- Slow, Not Broken
- DHCP Scope Eats the Server Block
- DHCP Hands Out the Wrong Gateway
- EIGRP - Fix R2 (3-Router Chain)
- Static Route Outranks OSPF
- iBGP Route Learned but Never Installed
- The Accounting VLAN Went Quiet After a Cable Audit
- The Patch Panel Labels Are Wrong
- Small Packets Fine, Large Packets Gone
- OSPF Area Mismatch on a New Link
- OSPF Stuck in ExStart
- The Protocol That Loses Your Subnet Masks
- Shared-Segment Wrong Next-Hop
- Overbroad Summary Route Blackhole
- One Server, Wrong Exit Interface
- The Route That Isn't There
- Tagged Port, Untagged Host
- Trunk Missing a VLAN
- Access Port in the Wrong VLAN
- Allow Access to Wiki Replica
Assess
Graded quizzes
20 graded questions across 10 quizzes, taken inside the modules above. Wrong answers explain the specific misconception behind the option you chose.
Review
Spaced repetition
Troubleshooting is tracked on the review ladder. Once you have answered a question on it, it comes back on a schedule that stretches as you keep getting it right - and resets if you don't. See your review queue.
Certification
Exam objectives this topic covers
- 2.1 Configure and verify VLANs (normal range) spanning multiple switches
- 2.2 Configure and verify interswitch connectivity (trunks, 802.1Q, native VLAN)
- 2.3 Configure and verify Layer 2 discovery protocols (CDP, LLDP)
- 3.1 Interpret the components of a routing table
- 3.2 Determine how a router makes a forwarding decision by default
- 3.4 Configure and verify single area OSPFv2
- 4.1 Configure and verify inside source NAT using static and pools
- 4.3 Explain the role of DHCP and DNS within the network
- 4.4 Explain the function of SNMP in network operations
- 4.5 Describe the use of syslog features including facilities and levels
- 4.6 Configure and verify DHCP client and relay
- 4.9 Describe the capabilities and function of TFTP/FTP in the network
- 1.1 Explain concepts related to the OSI reference model
- 2.1 Explain characteristics of routing technologies
- 2.2 Given a scenario, configure switching technologies and features
- 3.1 Explain the purpose of organizational processes and procedures
- 3.3 Explain disaster recovery concepts
- 3.4 Given a scenario, implement IPv4 and IPv6 network services
- 5.1 Explain the troubleshooting methodology
- 5.3 Given a scenario, troubleshoot common issues with network services
- 5.4 Given a scenario, troubleshoot common performance issues
- 5.5 Given a scenario, troubleshoot and resolve general networking issues