TRACEROUTE

✅ What is Traceroute?

Traceroute is a network utility used to trace the path that packets take from your computer to a target server/host. It shows each hop (router) along the way and how long each step takes.

👉 In simple terms:

• Shows how data travels through the Internet to reach a destination.

• Helps find where a connection slows down or breaks.

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🔑 Why is Traceroute Important?

Purpose	Why it matters
Diagnose network problems	Find where connection drops or slows.
Measure latency per hop	Identify slow network devices or congestion.
Understand network route	See how data travels to a destination.
Check ISP and intermediary routers	Identify which ISPs/routers your data passes through.

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⚙️ How does Traceroute Work?

1. Sends packets with increasing TTL (Time-To-Live) values.

2. Each router (hop) along the path decrements TTL by 1.

3. When TTL reaches 0, router sends ICMP "Time Exceeded" reply.

4. By analyzing replies, traceroute maps the path to the destination.

📊 Example:

• TTL = 1 → Stop at 1st router, get reply.

• TTL = 2 → Stop at 2nd router, get reply.

• Continue until reaching target server.

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💻 Traceroute Commands:

System	Command Example
Windows	tracert google.com
Linux/Mac	traceroute google.com

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📜 Example Output (Windows - tracert):

nginxCopyEditTracing route to google.com [142.250.190.78]
over a maximum of 30 hops:

  1    2 ms     1 ms     2 ms  192.168.1.1
  2    5 ms     3 ms     4 ms  10.0.0.1
  3   20 ms    15 ms    17 ms  isp-gateway.net [203.0.113.1]
  4   35 ms    30 ms    40 ms  142.250.190.78

Trace complete.

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📜 Example Output (Linux/Mac - traceroute):

nginxCopyEdittraceroute to google.com (142.250.190.78), 30 hops max
 1  192.168.1.1 (192.168.1.1)  2.123 ms  1.987 ms  2.055 ms
 2  10.0.0.1 (10.0.0.1)  5.567 ms  5.432 ms  5.678 ms
 3  isp-gateway.net (203.0.113.1)  15.345 ms  14.876 ms  15.654 ms
 4  142.250.190.78 (142.250.190.78)  30.987 ms  31.345 ms  30.543 ms

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🧠 Key Terms in Output:

Term	Meaning
Hop Number	Order of devices in the route.
IP Address	Address of the router or device.
Hostname	(Optional) Domain name of the router.
Time (ms)	Round-trip time to that router (latency).
* (Asterisk)	Timeout / No reply received from that hop.

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🛠️ Traceroute Common Options:

Option	Description	Example
-d (Windows)	Do not resolve addresses to hostnames.	tracert -d google.com
-h [max hops]	Set max number of hops.	tracert -h 20 google.com
-w [timeout] (ms)	Set timeout for each reply.	tracert -w 500 google.com
-n (Linux/Mac)	Don't resolve names (show IP only).	traceroute -n google.com
-m [max hops]	Set max hops (Linux/Mac).	traceroute -m 20 google.com
-q [queries]	Number of queries per hop (Linux/Mac).	traceroute -q 5 google.com

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🚦 How to Interpret Traceroute Results:

Scenario	Meaning
Normal response with times	Hop is reachable; latency measured.
* * * (3 stars)	No response; hop is dropping/ignoring packets.
High response times	Possible congestion or slow device.
Sudden jump in time between hops	Bottleneck or delay introduced.
Stops before reaching target	Possible routing issue or firewall blocking.

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📌 Use Cases of Traceroute:

1. Identify network slowdowns:

bashCopyEdittracert youtube.com

1. Find broken paths (packet drop):

bashCopyEdittraceroute facebook.com

1. Check international routing:

bashCopyEdittraceroute cnn.com

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🔐 Traceroute vs Ping:

Feature	Ping	Traceroute
Purpose	Test if host is reachable.	Trace the route packets take to a host.
Shows hops?	❌ No	✅ Yes
Shows delay per hop?	❌ No	✅ Yes
Packet type	ICMP Echo Request/Reply	ICMP (Windows), UDP/ICMP (Linux/Mac)

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✅ Summary:

Feature	Description
Purpose	Trace path of packets to destination.
Diagnoses	Network delays, unreachable devices.
Command (Windows)	tracert [host]
Command (Linux/Mac)	traceroute [host]
Common Issues Found	Slow hops, dropped packets, broken routes.