How to Use Traceroute with TCP, UDP, and ICMP Protocols (Made Simple)

Imagine you’re sending a letter to a friend across the country. It doesn’t go straight to them—it passes through several post offices along the way. Each post office stamps the letter and sends it to the next one until it reaches your friend. Now, what if the letter takes too long to arrive? You’d want to know where it got stuck. That’s exactly what traceroute does for your internet connection—it shows you the path your data takes to reach a website or server and helps you spot where delays happen.

Traceroute is like a detective tool for your internet. It sends small bits of data (called packets) to a destination, like a website, and tracks how long it takes for each “post office” (called a router) along the way to handle them. Normally, traceroute uses something called ICMP to do this, but sometimes networks block ICMP (like a post office refusing certain mail). That’s when you can switch to TCP or UDP—think of them as different types of envelopes that might get through when others don’t.

In this guide, we’ll explain how to use traceroute with ICMP, UDP, and TCP in simple terms, so you can figure out why your internet might be slow or why a website isn’t loading.

Why Use Different “Envelopes” (Protocols)?

Traceroute usually uses ICMP, which is like a standard envelope. But some networks are picky and won’t let ICMP envelopes through. That’s when you can try UDP or TCP, which are like special envelopes that might be allowed. Here’s why you’d pick each:

ICMP: The default choice—like sending a regular letter. It works most of the time.

UDP: A backup option—like sending a postcard when the letter gets blocked.

TCP: Great for checking specific services, like seeing if a website’s “mailbox” is open.

Knowing how to switch between these helps you get the job done, even when the usual way doesn’t work.

How Traceroute Works (in Simple Terms)

Traceroute sends out packets with a timer that counts down at each stop. Each router along the way reduces the timer and sends a message back, saying, “I got your packet, and here’s how long it took.” This repeats until the packet reaches the final destination. The result is a list of stops (hops) with times next to them, showing you the path and where any delays might be.

For example, if your data goes through 10 routers, traceroute will show you the time it took at each one. If one router took 200 milliseconds (ms) while the others took 20 ms, you’ve found the slow spot!

Using Traceroute with ICMP (The Standard Way)

ICMP is the go-to method for traceroute. Here’s how to use it:

On Windows:

Open the Command Prompt (search for “cmd” in the start menu).

Type tracert [website], like tracert google.com, and press Enter.

Wait for the list of hops to appear, showing times in milliseconds.

On Mac or Linux:

Open Terminal (found in Applications or via Spotlight).

Type traceroute -I [website], like traceroute -I google.com, and press Enter.

If you see a list of numbers and times, great! Each line is a stop along the way. But if you see stars (*) or the trace stops halfway, ICMP might be blocked, and it’s time to try another method.

Using Traceroute with UDP (The Backup Plan)

UDP is like sending a different kind of message that some networks prefer. It’s especially useful when ICMP doesn’t work.

On Windows:
Windows doesn’t have a built-in UDP traceroute, so you’ll need a free tool like htracert. Once installed, you can type htracert -u [website] to use UDP.

On Mac or Linux:

Open Terminal.

Type traceroute -U [website], like traceroute -U google.com.

If UDP works, you’ll see the same kind of list as with ICMP. If not, don’t worry—there’s another option.

Using Traceroute with TCP (For Specific Services)

TCP is like sending a message directly to a website’s front door (e.g., the web server). It’s perfect for checking if a specific service is reachable.

On Windows:
You’ll need a tool like tcptraceroute. After installing, type tcptraceroute [website] [port], such as tcptraceroute google.com 80 (port 80 is for websites).

On Mac or Linux:

Open Terminal.

Type traceroute -T [website], like traceroute -T google.com.

To check a specific port, add -p [port], such as traceroute -T -p 80 google.com.

TCP is handy when you want to see if a website or app is having trouble because of a network issue.

Understanding What You See

When traceroute finishes, you’ll see a list like this:

1  192.168.1.1  2 ms  

2  10.0.0.1     10 ms  

3  172.16.0.1   50 ms  

4  * * *  

5  203.0.113.1  100 ms 

Numbers 1-5: These are the stops (routers) your data passed through.

IP Addresses: Each stop has an address, like a street name.

Times (ms): How long it took for the packet to reach that stop and come back.

Stars (*): If you see stars, it means that stop didn’t respond—maybe it’s busy or blocking the message.

If one stop has a much higher time, like 200 ms when others are 20 ms, that’s likely where the slowdown is.

When to Use Each Method

ICMP: Use it first—it’s the easiest and works most of the time.

UDP: Try this if ICMP doesn’t work, like if you see lots of stars.

TCP: Use this to check specific things, like why a website won’t load.

Think of it like trying different doors to get into a building—if one’s locked, you try another.

Why This Matters for You

Even if you’re not a tech expert, knowing how to use traceroute can help you figure out why your internet is slow or why a website isn’t working. For example:

Slow Video Calls: Traceroute can show if there’s a delay halfway across the country.

Website Not Loading: It can reveal if the problem is on your end or the website’s.

If you find a slow spot, you can tell your internet provider (ISP) exactly where the issue is, which might speed up the fix.

Final Tips

Be Patient: Traceroute can take a minute or two to finish.

Run It a Few Times: Networks change, so try it more than once to confirm.

Don’t Panic Over Stars: A few stars are normal—some routers just don’t respond.

Traceroute is like a flashlight in the dark—it shows you where the problem is hiding. And the best part? You don’t need to be a tech whiz to use it. Just follow these steps, and you’ll be diagnosing your internet like a pro.