CCNA · Configuration · Troubleshooting
NetLab generates unlimited switching and routing labs, simulates the network you configure packet-path by packet-path, and grades your work against the running state of the topology.
SW1#show interfaces trunk Port Mode Encapsulation Status Native vlan Gi0/1 on 802.1q trunking 99 Port Vlans allowed on trunk Gi0/1 10,20,30,99 SW1#configure terminal SW1(config)#interface range gi0/2 - 4 SW1(config-if-range)#switchport mode access SW1(config-if-range)#switchport access vlan 20 SW1(config-if-range)#spanning-tree portfast SW1(config-if-range)#end SW1#ping 192.168.20.1 !!!!! Success rate is 100 percent (5/5)
Config modes, interface ranges, show running-config, ping and traceroute — parsed and simulated, not scripted.
Every lab is generated from a seed and validated as solvable before you see it. No repeated scenarios.
Working networks are broken by fault injection. Diagnose with show commands, then repair the config.
Scored against the actual simulated network state — reachability, adjacencies, VLAN membership and routing.
Labs build the hands, question banks build the recall. Every set is randomised from the bank and weighted toward the concepts you have missed before.
Pick any combination of topics, answer a 10-question set, and get an explanation for every answer — right or wrong.
45 minutes, free navigation, no feedback until you submit — then a per-topic score breakdown showing exactly where to revise.
Four difficulty tiers per topic, from guided beginner tasks to expert scenarios with minimal instruction.
IPv4 Addressing
Interface addressing, masks and gateways
Subnetting
Divide a network into equal blocks
VLSM
Right-size subnets to host requirements
VLANs
VLAN database, naming and membership
Access Ports
Edge port assignment and hardening
Trunking
802.1Q trunks, pruning and native VLANs
Inter-VLAN Routing
Router-on-a-stick gateways
Static Routing
Manual routes and return paths
Default Routes
Quad-zero routing to an upstream
OSPF
Single-area OSPF adjacencies
STP
Root bridge control and edge ports
EtherChannel
Link aggregation with LACP/PAgP
IPv6 Addressing
Global, link-local and prefix configuration
IPv6 Routing
IPv6 static and default routes
OSPF for IPv6
Configure and verify OSPFv3 area 0
DHCP
Pools, exclusions and client options
DHCP Relay
Helper addresses across VLANs
NAT
Static NAT, dynamic NAT and PAT
DNS & Network Services
DNS, NTP, Syslog and SNMP on IOS
ACLs
Extended access lists and traffic policy
IPv6 ACLs
Named IPv6 access lists and traffic-filter
Port Security
Sticky MAC learning and violation actions
SSH & Device Security
SSHv2, local users and hardened VTY lines
DHCP Snooping
Trusted ports and rogue server protection
Dynamic ARP Inspection
Validate ARP against DHCP bindings
CDP & LLDP
Neighbour discovery and port-level control
Advanced STP
Rapid-PVST, per-VLAN load sharing and edge guards
Advanced EtherChannel
Multiple bundles, LACP vs PAgP and trunk pruning
Wireless LANs
WLAN profiles, client VLANs and AP ports
Wireless Security
WPA2/WPA3, 802.1X and guest SSIDs
QoS
Classification, marking and priority queueing
Device Management
NTP, syslog and SNMP monitoring
Programmability
RESTCONF, NETCONF and secure API access
Troubleshooting
Diagnose and repair a broken network
Each topic has a free command reference: syntax, verification commands and common mistakes.