Chapter 35: Bash ping

What does ping actually do? (super simple first)

ping = checks if another computer/device/server is reachable over the network and measures how long it takes for a message to go there and come back.

Think of it like this:

• You shout “Hello!” from your house to your friend’s house across the street.
• If he shouts “Hi!” back → he’s alive/reachable.
• You count how many seconds it took for the sound to go and come back → that’s the round-trip time (latency).

In networking, ping sends small test packets (called ICMP Echo Request) to an IP address or domain name, and waits for ICMP Echo Reply.

If you get replies → the destination is alive and network path is working. If no reply → either destination is down, firewall is blocking, or network problem.

Why do we use ping? (real reasons you will use it daily)

• Check if your internet is working
• See if a website/server is down (YouTube not loading? ping youtube.com)
• Measure latency (delay) – very important for gaming, video calls, trading apps
• Find if problem is in your Wi-Fi, ISP, or far-away server
• Test DNS (if ping 8.8.8.8 works but ping google.com fails → DNS issue)
• Quick network troubleshooting (most first step when something is slow/offline)

1. Basic usage (try right now!)

Example output you might see:

Press Ctrl+C to stop (otherwise it runs forever).

2. Understand every line (very important!)

3. Most useful options (you’ll use these 90% of time)

4. Real-life examples you will use daily (Hyderabad style)

• Internet not working? Start here:
  Bash

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  ping 8.8.8.8 -c 4 # If works → internet is up, problem is DNS or app ping google.com -c 4 # If this fails → DNS issue (change to 8.8.8.8 in settings)

• BGMI / COD laggy? Check latency:
  Bash

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  ping delhi.pubgmobile.com -c 10 # or find server IP from game logs # avg time > 100–150 ms → lag (common on Jio 4G/5G sometimes)

• Website not opening?
  Bash

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  ping www.instagram.com -c 4 # If 100% loss → site down or your ISP blocking

• Check your router is alive:
  Bash

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  ping 192.168.1.1 -c 4     # most home routers # or ping your default gateway (find with ip route)

• Test Wi-Fi stability (packet loss):
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  ping -c 100 8.8.8.8 | grep loss # Look for >2–3% loss → bad Wi-Fi signal or interference

5. Quick cheat-sheet table

6. Pro tips & common gotchas

• Firewall blocks ping → many servers (especially cloud) block ICMP → 100% loss doesn’t always mean down (try curl google.com instead)
• High latency on mobile data → normal (Jio/Airtel 4G/5G often 30–100 ms)
• Packet loss >5% → bad Wi-Fi, faulty cable, ISP issue, or overloaded network
• mdev high (jitter) → unstable connection (video call will stutter)
• Alternative modern tool: mtr (combines ping + traceroute)
  Bash

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  sudo apt install mtr mtr google.com

Now open your terminal and try these 3 right now:

Tell me:

• What’s your average time to 8.8.8.8? (e.g. 22 ms)
• Any packet loss?

Or ask:

• “Why does ping youtube.com work but website not opening?”
• “How to ping from phone?”
• “What is good ping for BGMI / Free Fire?”

We’ll troubleshoot together! 😄