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CCNA Subnetting with VLSM Guide

May 21, 2025

Jeremy's IT Lab: CCNA Subnetting with VLSM

Introduction

  • Complete course for CCNA
  • Subscribe, like, comment, and share to support the series
  • Download the practice lab and try it in packet tracer

Lab Overview

  • Focus: Subnetting using VLSM (Variable-Length Subnet Masks)
  • Task: Subnet a Class C network into 5 different-sized subnets
  • Network: 192.168.5.0/24
  • Subnets to assign: LAN2, LAN1, LAN3, LAN4, Point-to-point link between R1 and R2
  • Assign first usable address to the PC and the last to the router

Subnetting Process

  • LAN2
    • Use a /25 prefix length
    • Network address: 192.168.5.0
    • Broadcast address: 192.168.5.127
    • R1 IP: 192.168.5.126
    • PC2 IP: 192.168.5.1
  • LAN1
    • Use a /26 prefix length
    • Network address: 192.168.5.128
    • Broadcast address: 192.168.5.191
    • R1 IP: 192.168.5.190
    • PC1 IP: 192.168.5.129
  • LAN3
    • Use a /28 prefix length
    • Network address: 192.168.5.192
    • Broadcast address: 192.168.5.207
    • R2 IP: 192.168.5.206
    • PC3 IP: 192.168.5.193
  • LAN4
    • Use a /28 prefix length
    • Network address: 192.168.5.208
    • Broadcast address: 192.168.5.223
    • R2 IP: 192.168.5.222
    • PC4 IP: 192.168.5.209
  • Point-to-point Link (R1 and R2)
    • Use a /30 prefix length
    • Network address: 192.168.5.224
    • Broadcast address: 192.168.5.227
    • R1 IP: 192.168.5.225
    • R2 IP: 192.168.5.226

Configuration Steps

  • For Routers (R1 and R2):
    • Enable and configure interfaces using the IP addresses from above
    • Use NO SHUTDOWN to activate interfaces
    • Verify with DO SHOW IP INTERFACE command
  • For PCs (PC1, PC2, PC3, PC4):
    • Set gateway to router’s IP
    • Configure IP address and subnet mask

Static Route Configuration

  • On R2:
    • Route to LAN1: IP ROUTE 192.168.5.128 255.255.255.192 192.168.5.225
    • Route to LAN2: IP ROUTE 192.168.5.0 255.255.255.128 192.168.5.225
    • Verify routes with DO SHOW IP ROUTE
  • On R1:
    • Route to LAN3: IP ROUTE 192.168.5.192 255.255.255.240 192.168.5.226
    • Route to LAN4: IP ROUTE 192.168.5.208 255.255.255.240 192.168.5.226
    • Verify routes with DO SHOW IP ROUTE

Verification

  • Perform ping tests between PCs to ensure connectivity
  • Note any initial ARP process delays

Conclusion

  • Successfully subnetted and configured a network
  • Ensured reachability with static routes
  • Encourage feedback and support through video interactions and tips
  • Mention of Brave verified publisher and BAT tips

Note: Details like the broadcast address of 255.255.255.255 are explained briefly with emphasis on the behavior of broadcasts in networks. More detailed explanations might follow in subsequent lectures.

Full transcript