🧠🖥️ Cisco Device SHOW Commands

Show commands are the eyes of a network engineer. They allow you to view configuration, status, routing, hardware, and traffic without changing anything. All examples below are based on devices from Cisco Systems.

🔑 What Are show Commands?

Show commands are used to:

• Verify configuration
• Check device health
• Troubleshoot problems
• Collect information (Help Desk & NOC work)

1️⃣ show running-config (show run)

📌 Purpose

Displays the current active configuration stored in RAM.

    show running-config
      

🔍 What You See

• Hostname
• Interface IP addresses
• VLANs
• Routing protocols
• Encrypted passwords
• Access control lists

🧪 Example Use

❓ Users can’t access the internet

• Check IP configuration
• Default gateway
• NAT
• VLAN assignments

2️⃣ show cdp neighbors

📌 Purpose

Shows directly connected Cisco devices using CDP (Cisco Discovery Protocol).

    show cdp neighbors
      

🔍 What You See

• Neighbor device name
• Device type (switch / router)
• Local interface
• Remote interface

🧪 Example Use

❓ Which switch is connected to this port?

✔ Use show cdp neighbors

3️⃣ show ip interface brief

📌 Purpose

Provides a quick summary of all interfaces and their status.

    show ip interface brief
      

🔍 Columns Explained

🧠 Important States

• up / up ✅ → Working
• down / down ❌ → Cable or power issue
• up / down ⚠️ → Configuration issue

4️⃣ show ip route

📌 Purpose

Displays the routing table and how packets are forwarded.

    show ip route
      

🔍 What You Learn

• Connected routes
• Static routes
• Default route (0.0.0.0/0)
• Dynamic routes

🧪 Example Use

❓ Network can’t reach the internet

✔ Check if default route exists

5️⃣ show version

📌 Purpose

Displays device and operating system information.

    show version
      

🔍 Displays

• IOS version
• Device model
• RAM & flash
• Uptime
• Serial number (sometimes)

6️⃣ show inventory

📌 Purpose

Displays detailed hardware inventory information.

    show inventory
      

🔍 Displays

• Product ID (PID)
• Serial numbers
• Modules
• Power supplies

🧪 Example Use

• Asset management
• Warranty checks

7️⃣ show mac address-table

📌 Purpose

Displays MAC addresses learned by the switch.

    show mac address-table
      

🔍 Shows

• MAC address
• VLAN
• Port

🧪 Example Use

❓ Which port is this PC connected to?

✔ Find MAC → identify port

8️⃣ show interface / show interface status

📌 Purpose

Shows detailed interface statistics and health.

    show interface fa0/1
    show interface status
      

🔍 What You See

• Speed & duplex
• Errors (CRC, collisions)
• Bandwidth usage
• Link state

🧪 Example Use

❓ Network is slow

• Check errors
• Check speed mismatch

🔐 9️⃣ Privilege Levels

📌 What Are Privilege Levels?

Privilege levels control what commands a user can execute.

    enable
    disable
      

❓ 🔟 Command Help & Auto-Complete

📌 Help Feature (?)

    show ?
      

✔ Lists all possible command options

📌 Auto-Complete (TAB)

    sho<TAB>
      

✔ Completes to show

🧠 BIG PICTURE: Which Command for What?