CCNA Lab 2: Subnet a /24 into Four /26s

Bundle lab

Hands-on IPv4 subnetting and interface addressing on three IOS routers and one client. You will split a /24 into four equal /26s, assign the correct /26 mask to each link, and configure deterministic lowest-usable addressing on router interfaces. No routing protocols or static routes are used; verification is strictly directly-connected reachability.

Learning objectives

• Perform correct /24 to /26 subnetting and identify subnet boundaries
• Apply deterministic IPv4 interface addressing on IOS with dotted-decimal masks
• Map each link to its assigned subnet based on an allocation rule
• Verify directly-connected reachability without any routing protocol or static routes
• Use show commands to confirm interface state and addressing

Troubleshooting focus

• A neighbor ping fails across a router-to-router link: compare both ends with show ip interface brief. A /24 on one side and a /26 on the other puts the two interfaces in different subnets.
• An interface reads administratively down in show ip interface brief: it was never enabled. Apply no shutdown on every participating interface.
• The ping still fails although both ends show the same /26 mask: one address sits outside the intended /26, or is that subnet's network or broadcast address. Re-check the subnet math and take the lowest usable host address per the allocation rule.
• CLIENT01 cannot ping its default gateway: confirm the RTR-BR3 LAN interface address matches the host's configured gateway and that the interface is up/up.
• A ping to a device two hops away fails: expected here. There is no routing beyond each directly-connected segment, so test only immediately-adjacent devices.