Here's a trap I see all the time: The Mistake: Students calculate the subnet mask perfectly... then forget to check if the IP is actually IN that subnet. Example: IP: 192.168.10.50 /26 Subnet: 192.168.10.0 - 192.168.10.63 Looks good, right? But what if the question asks: "Is 192.168.10.75 in the same subnet?" The Fix: ALWAYS identify the range FIRST: - Network: .0 - First Host: .1 - Last Host: .62 - Broadcast: .63 NOW you can see .75 is NOT in this subnet. Pro Tip: Draw the range on paper during exams. Takes 5 seconds, saves points. What's YOUR biggest subnetting struggle? Drop it below 👇

This is something I have seen SO many times when teaching live classes. A student puts up their hand and tells me they configured everything perfectly, but can't ping anything, and they are now losing their mind. Well, they are not losing their mind, they just forgot one command... "no shutdown" interface gi0/1 no shutdown Cisco interfaces are administratively down by default. ALWAYS check: show ip interface brief (shortened: sh ip int bri) If you see "administratively down" → You forgot "no shutdown" How many of you have lost hours to this? 🤦‍♂️ Drop a 😅 if this has happened to you!