🌐 CMD Commands Used in Networking 

🖥 1️⃣ ipconfig

📖 Purpose

Shows the computer’s IP address, Subnet Mask, and Default Gateway for each network adapter (Wi-Fi, Ethernet, etc.).

It helps you:

1. See your IP address, gateway, subnet mask.
2. Reset or renew your IP.
3. Fix DNS-related problems.

🔧 Practical Usage

✅ 1. Check IP Configuration

ipconfig

Used to verify:

• IP Address
• Subnet Mask
• Default Gateway

👉 Helps confirm whether system received valid IP.

✅ 2. Detailed Information

ipconfig /all

Shows:

• Physical (MAC) address
• DHCP enabled or not
• DNS server
• Lease time

👉 Used in troubleshooting DHCP & DNS issues.

✅ 3. Release IP Address

ipconfig /release

Releases current DHCP IP address.

👉 Used when system has wrong IP or conflict.

✅ 4. Renew IP Address

ipconfig /renew

Requests new IP from DHCP server.

👉 Used when system shows APIPA (169.254.x.x).

🌐 2️⃣ ping

📖 Purpose

• Tests connectivity between your device and another device.
• It is used to test the connectivity, whether my device is able to communicate to the other devices or not
• Getting the reply – ensures the proper connection with the other device
• Not getting the reply  – Network problem (device is unreachable, off or blocked)

🔧 Practical Usage

ping 8.8.8.8
ping google.com

What It Checks:

• Network connectivity
• Packet loss
• Response time (latency)

Common Scenarios:

👉 Used to verify whether the issue is:

• Local network problem
• Gateway issue
• Internet issue

🌍 3️⃣ nslookup

📖 Purpose

The nslookup command is used to query DNS (Domain Name System) servers to get information about domain names and IP addresses.

• It helps you find the IP address of a domain name (forward lookup) – Example : nslookup google.com
• Or find the domain name of an IP address (reverse lookup) – E.xample : nslookup 8.8.8.8
• It can also show details of the DNS server being used.

Uses:-

• To check if a domain name is resolving properly.
• To troubleshoot DNS issues.
• To find the IP address of a website

🔧 Practical Usage

nslookup google.com

What It Checks:

• Domain name to IP resolution
• Which DNS server responded
• Whether DNS is working properly

👉 If ping fails but nslookup works → Internet OK, but routing issue.
👉 If nslookup fails → DNS problem.

📊 4️⃣ netstat

📖 Purpose

The netstat command is used to display active network connections and statistics. 

It shows :-

• Active connections - who your computer is connected to.
• Listening ports - open ports waiting for a connection.
• Protocol usage (TCP, UDP, ICMP, etc.).
• Network statistics (packets sent/received, errors).

Uses:

• To check if a domain name is resolving properly.
• To troubleshoot DNS issues.
• To find the IP address of a website.

🔧 Practical Usage

netstat -an

What It Shows:

• Active TCP/UDP connections
• Listening ports
• Foreign addresses

Useful for:

• Checking if the application is using a port
• Identifying malware connections
• Troubleshooting server port issues

🛣 5️⃣ tracert

📖 Purpose

It shows the path that data packets take from your computer to a destination and also measures the time taken at each hop.

Uses:

• Troubleshooting network connectivity issues
• Finding where the network is slow or failing
• Checking the path taken to reach a server
• Detecting if there’s a bottleneck in your network

🔧 Practical Usage

tracert google.com

What It Shows:

• Number of hops
• Routers in the path
• Delay at each hop

🔁 6️⃣ arp

📖 Purpose

• Shows the ARP table
• ARP table stores the mapping of IP addresses to the MAC address of devices in a LAN

NOTE : It do not include all the devices present in LAN, it only shows the mapping for the devices that your local computer recently communicated with or tried to.

🔧 Practical Usage

arp -a

à Shows the IP address and MAC address of the devices present in LAN

What It Shows:

• IP address
• Corresponding MAC address
• Interface

Used For:

• Detecting IP conflicts
• Verifying device MAC address
• Checking local network communication

🛤 7️⃣ route print

📖 Purpose

• The route command is used to view and manipulate the routing table of your computer.
• The routing table tells your system where to send network packets based on the destination IP address.

🔧 Practical Usage

route print

• It shows the routing table
• It shows a list of all the routes (paths) your computer uses to send data packets across networks.

What It Shows:

• Network destination
• Netmask
• Gateway
• Interface
• Metric

Used For:

• Checking default gateway (0.0.0.0)
• Diagnosing routing problems
• Verifying static routes

🧠 How to Troubleshoot Step-by-Step (Very Important)

If the internet is not working:

1️⃣ ipconfig → Check IP address
2️⃣ ping 127.0.0.1 → Check local TCP/IP
3️⃣ ping default gateway → Check router connectivity
4️⃣ ping 8.8.8.8 → Check internet
5️⃣ nslookup google.com → Check DNS
6️⃣ tracert google.com → Check routing path

🎓 Interview Question

❓ How do you troubleshoot when the internet is not working?

First, I check IP configuration using ipconfig, then verify connectivity using ping, check DNS using nslookup, and analyze routing using tracert and route print.