IPv4 VLSM: Overlapping Subnets
VLSM conserves address space only when every prefix boundary is calculated correctly. This lab pairs subnet math with the operational symptoms of overlapping address plans.
The problem
A new /27 was allocated inside an existing /26 range. Hosts on the two segments have inconsistent reachability because the address plan overlaps.
What you'll practice
- Calculate /26 and /27 boundaries
- Identify overlapping IPv4 ranges
- Interpret interface addressing
- Apply a corrected address plan
The topology
A router connects two LANs that should be distinct VLSM subnets but overlap due to an incorrect network boundary.
Commands to run yourself
The real diagnostic commands for this lab, copy-paste ready. Run these in the same order to reproduce the investigation on your own session.
show ip interface briefshow ip route connectedTopology diagram
Frequently asked
Is this aligned to CCNA practice?
Yes. It focuses on configuration, verification, and troubleshooting skills covered by the CCNA-level technology domain named on this lab.
Ready to run this lab yourself?
No setup, no image sourcing. Book a session or ask for a live demo.