ping — Check connection reachability

💬 "ping command"

ping checks reachability and latency. It is the first step in diagnosing network problems.

In environments where ICMP is blocked, a ping failure may not indicate a service problem.

• Concept: Measures round-trip time using ICMP echo request/response.
• time: Round-trip latency. A sudden increase indicates a segment problem.
• packet loss: Loss rate. 0% is normal.
• Statistics: Summarizes minimum/average/maximum latency and loss on exit.

Commonly used options

3 essential command combinations

• ping -c 4 10.0.0.9 — Check internal server reachability
• ping -c 10 -i 0.2 8.8.8.8 — Check external connectivity and loss
• ping -M do -s 1472 10.0.0.9 — Check MTU (fragmentation) issues

💬 "Show me an example of checking with minimal commands in an emergency"

Here are common situations on production servers, organized in order.

Step 1 · Gateway

Start by checking the closest target.

ping -c 3 10.0.1.1

Step 2 · Target server

Check reachability to the target server.

ping -c 4 10.0.0.9

Step 3 · Latency trend

Observe latency/loss trends by repeating measurements.

ping -c 20 -i 0.2 10.0.0.9

How this is used in practice

1. Service connection latency

Situation — Web responses are intermittently slow.

ping -c 20 -i 0.2 10.0.0.9

Result — Check whether average latency and packet loss are within normal ranges.

Point — If ping works but the service is slow, look at the application/DB segment.

2. ICMP-blocked environments

Situation — Ping does not work, but the service is fine.

ping -c 3 -W 2 10.0.0.9 ; curl -sI -m 3 https://10.0.0.9 | head -1

Result — Confirm that ICMP is blocked, but HTTPS responds.

Point — Checking reachability via the actual service port (TCP) is more accurate.

Important notes

• In ICMP-blocked environments, ping failure does not mean an outage.
• An endless ping never terminates, so use -c for automation.
• Sending excessive ICMP traffic can lead to blocking or warnings.

Actual execution output

This is the result of checking internal server reachability and latency.

!ping command execution result: reachability and latency

Production server

Source (HTML): https://games.aidebatehub.com/programs/linux/network/ping.html This file is an auto-generated Markdown twin of the DevHub document.