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Examples with Explanations

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Here are practical examples of how to use the most common network diagnostic commands, along with guidance on interpreting their results.

Example 1: Testing Website Connectivity #

Command:

bash

ping example.com

What happens:

  • Sends 10 ping packets to the domain.
  • Measures response time for each packet.
  • Calculates average, minimum, and maximum times.
  • Reports packet loss percentage.

What to look for:

  • Average response time (lower is better).
  • Packet loss (should be 0% or very low).
  • Connection quality grade (A–F).

If results are good:

  • Server is reachable.
  • Connection is stable.
  • No network issues detected.

If results are poor:

  • High response times → Slow connection or distant server.
  • Packet loss → Connection problems.
  • Use traceroute to locate where issues occur.

Example 2: Checking DNS Resolution #

Command:

bash

nslookup example.com

What happens:

  • Queries your default DNS server.
  • Retrieves the IP address for the domain.
  • Displays which DNS server was used.

What to look for:

  • IP address returned (indicates DNS works).
  • DNS server used.
  • Response time.

If it works:

  • DNS is resolving correctly.
  • Domain points to the correct IP.

If it fails:

  • DNS problem detected.
  • Try another server:bashnslookup example.com 8.8.8.8
  • If that works, your default DNS server has issues.

Example 3: Finding Network Bottlenecks #

Command:

bash

traceroute example.com

What happens:

  • Displays each router (hop) along the path.
  • Measures response time to each hop.
  • Identifies where delays occur.

What to look for:

  • Sudden increase in time → Bottleneck.
  • * * * → Router not responding (usually normal).
  • High times early → Local network/ISP issue.
  • High times late → Destination network issue.

How to read:

Code

1. 192.168.1.1 (2ms) - Your router (fast)<br>2. 10.0.0.1 (8ms) - ISP gateway (fast)<br>3. 203.0.113.1 (150ms) - Sudden jump! Bottleneck here<br>4. 198.51.100.1 (155ms) - Still slow<br>5. 93.184.216.34 (160ms) - Destination

Example 4: Detailed DNS Information #

Command:

bash

dig example.com

What happens:

  • Performs a comprehensive DNS query.
  • Displays query time, server, and all record types.
  • Provides authority and additional sections.

What to look for:

  • Query time (lower is better).
  • Answer section (IP addresses).
  • Authority section (nameservers).
  • TTL values (cache duration).

Use cases:

  • Need more detail than nslookup.
  • Check DNS performance.
  • Verify all record types.
  • Troubleshoot DNS issues.

Example 5: Domain Registration Info #

Command:

bash

whois example.com

What happens:

  • Queries the WHOIS database.
  • Retrieves domain registration details.
  • Displays registrar, registration/expiration dates, nameservers, and status.

What to look for:

  • Expiration date (when renewal is required).
  • Registrar (who manages the domain).
  • Nameservers (DNS servers in use).
  • Status (domain lock, transfer status).

Use cases:

  • Check when a domain expires.
  • Find domain owner (if public).
  • Verify nameserver configuration.
  • Research domain details for auditing or troubleshooting.

This set of examples gives you a practical workflow for diagnosing connectivity, DNS, routing, and domain registration issues.