Definition

The tracert command (short for “trace route”) is a network diagnostic tool used to track the pathway that a packet of data takes from your computer to a destination host, such as a website or server. It is available on Windows, while the equivalent command on Unix-like systems (Linux, macOS) is traceroute.

Purpose and Usage

The primary purpose of tracert is to identify the route and measure the transit delays of packets across an IP network. It is helpful for diagnosing network connectivity issues and pinpointing where packets are being delayed or lost.

How It Works

Sending Packets with Incrementing TTL: tracert works by sending a series of Internet Control Message Protocol (ICMP) Echo Request packets to the destination with varying Time-To-Live (TTL) values. The TTL value starts at 1 and increments by 1 with each subsequent packet.
ICMP Time Exceeded Messages: Each router that handles a packet decrements the TTL by 1. When the TTL reaches 0, the router discards the packet and sends an ICMP Time Exceeded message back to the source. This way, tracert can identify each hop along the path to the destination.
Final Destination: When the packet finally reaches the destination, it sends an ICMP Echo Reply message, indicating that the destination has been reached.

Common Usage and Options

Basic Syntax

tracert [hostname or IP address]

Example

To trace the route to example.com:

tracert example.com

Options

-d: Prevents tracert from resolving IP addresses to hostnames. This speeds up the process as DNS resolution is not performed.
```
tracert -d example.com
```
-h maximum_hops: Specifies the maximum number of hops to search for the target (default is 30).
```
tracert -h 15 example.com
```
-w timeout: Sets the timeout period (in milliseconds) for each reply (default is 4000 ms).
```
tracert -w 1000 example.com
```
-4: Forces tracert to use IPv4.
```
tracert -4 example.com
```
-6: Forces tracert to use IPv6.
```
tracert -6 example.com
```

Interpreting the Output

The output of tracert typically includes:

Hop Number: The position in the path (starting at 1 for the first hop).
Round Trip Time (RTT): The time it takes for the packet to go to the hop and back, usually displayed in milliseconds.
IP Address: The IP address of the router or gateway at that hop.
Hostname: The resolved hostname (if DNS resolution is enabled).

Example output:

Tracing route to example.com [93.184.216.34] over a maximum of 30 hops:

  1    1 ms    1 ms    1 ms  192.168.1.1
  2   15 ms   14 ms   15 ms  203.0.113.1
  3   23 ms   23 ms   23 ms  198.51.100.1
  4   25 ms   25 ms   25 ms  example.com [93.184.216.34]

Trace complete.

Conclusion

tracert is a valuable tool for network administrators and anyone troubleshooting network issues, providing insights into the path and performance of network routes to remote hosts.

References

Information

date: 2024.08.06
time: 18:25

🪴 TJ's Notes 1.0

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