What Is a Traceroute? How to Run One and Read the Results

Your speed test says 300 Mbps, but Zoom keeps freezing. You restart your router, swap cables, even call your ISP — nothing helps. The problem is that a speed test only measures the endpoints. It tells you how fast data moves between your device and a nearby test server. It says nothing about the 20–30 routers in between that your data actually passes through on the way to Zoom, your game server, or Netflix.

A traceroute exposes that entire path. It sends packets with incrementally increasing time-to-live (TTL) values so that each router along the route identifies itself and reports how long the round trip took. The result is a hop-by-hop map of your connection — complete with latency measurements at every stop.

If one of those routers is congested, misconfigured, or failing, traceroute shows you exactly where the breakdown is. That is information your ISP's support team can actually act on — and it is the difference between "my internet is slow" (which gets you a script reset) and "there is a 180 ms latency spike at hop 7 on your Houston backbone router" (which gets you escalated).

How Does a Traceroute Actually Work?

Every IP packet has a field called TTL (Time to Live). Despite the name, it is not a timer — it is a hop counter. Each router that handles the packet decreases the TTL by one. When the TTL hits zero, the router discards the packet and sends back an ICMP "Time Exceeded" message to the sender, including the router's IP address.

Traceroute exploits this behavior. It sends the first packet with TTL = 1, so the very first router drops it and identifies itself. The next packet goes out with TTL = 2, reaching the second router before being dropped. This continues until a packet finally reaches the destination server, which replies with a different ICMP message ("Port Unreachable" on Linux/Mac or "Echo Reply" on Windows). The result is a complete list of every router between you and the target.

ICMP vs UDP vs TCP Traceroute

The method matters because some routers and firewalls treat different packet types differently. If you see a row of asterisks (***) in your output, switching from ICMP to TCP traceroute often reveals the hidden hops.

How to Run a Traceroute on Any Device

Windows

1. Press Windows + R, type cmd, and press Enter
2. Type tracert google.com (or any destination) and press Enter
3. Wait for all hops to resolve — this can take 30–60 seconds

macOS

1. Open Terminal (Applications → Utilities → Terminal)
2. Type traceroute google.com and press Enter
3. Wait for the output to complete (press Ctrl+C to stop early if needed)

Linux

1. Open a terminal window
2. Type traceroute google.com and press Enter
3. For TCP mode (bypasses more firewalls): sudo traceroute -T google.com

Online (No Install Needed)

If you do not want to open a terminal, Pong.com has a free visual traceroute tool at pong.com/traceroute. It runs a traceroute from our servers and displays the results in a clean, color-coded interface — no command line required. This is also useful for comparing the route from our infrastructure to a destination versus the route from your own device.

How to Read Traceroute Results: Line by Line

A typical traceroute line looks like this:

Each line has four pieces of information, and every one of them is useful:

What the Router Names Tell You

Router hostnames often encode useful information. A name like ae-5-5.ebr2.Dallas1.Level3.net tells you this is a Level 3 (now Lumen) backbone router in Dallas. Similarly, be3039.ccr42.iad30.atlas.cogentco.com is a Cogent router in the IAD (Washington Dulles) area. City codes in router names help you understand the geographic path your data is taking — if you are in New York trying to reach a server in New York but your traceroute shows hops through Dallas and Los Angeles, that is an inefficient route.

What Do Normal Traceroute Results Look Like?

A healthy traceroute has three characteristics: latency increases gradually with each hop, all three RTT values are close together at each hop, and no hops show timeouts.

5 Red Flags in Traceroute Results (and What They Mean)

1. Sudden Latency Spike That Persists

If latency jumps from 25 ms to 180 ms at hop 6 and stays high for all subsequent hops, the router at hop 6 (or the link between hop 5 and 6) is the bottleneck. This is the most common and most actionable finding in a traceroute. Note which ISP or backbone provider owns that hop — it tells you who is responsible for the problem.

2. Latency Spike at a Single Hop That Recovers

If hop 6 shows 180 ms but hop 7 drops back to 30 ms, the router at hop 6 is probably just deprioritizing ICMP responses. Many routers handle traceroute/ping packets at low priority because their real job is forwarding actual traffic. This is almost always harmless — do not panic about a single slow hop if the rest of the route looks clean.

3. Asterisks (* * *) at Multiple Consecutive Hops

A single row of asterisks usually means a router is configured to silently drop ICMP packets (common with firewalls and cloud providers). But multiple consecutive timeouts, especially at the end of the traceroute, indicate a real routing failure or firewall block. If the final destination also times out, the server may be down or blocking your traffic entirely.

4. Wildly Inconsistent RTT Values at One Hop

If a hop shows something like 12 ms 145 ms 18 ms, that extreme inconsistency signals jitter at that point in the path. The router is intermittently congested or experiencing buffer issues. This is especially bad for gaming and video calls, which need consistent latency more than low latency.

5. Routing Loops

If you see the same IP address appearing at multiple hops, or if latency suddenly decreases then increases again in a repeating pattern, your packets may be caught in a routing loop. This is a configuration error on the network side and is always worth reporting to your ISP.

Traceroute vs Ping: What's the Difference?

People often confuse traceroute and ping because both measure latency. But they answer fundamentally different questions:

Think of ping as a thermometer and traceroute as an X-ray. The thermometer tells you something is wrong. The X-ray shows you exactly where.

Real-World Traceroute Scenarios and What to Do

Scenario 1: Gaming Lag Despite Good Speed

You have 500 Mbps download but your ping to the game server is 90 ms when it should be 30 ms. Run a traceroute to the game server IP. If you see a latency spike at a peering point (where your ISP hands off to another network), your ISP's routing is taking an inefficient path. Call your ISP and ask them to check their BGP routes to that destination. Some ISPs will adjust routing if you provide the traceroute data.

Scenario 2: Video Calls Drop at the Same Time Every Day

Run traceroutes at different times — once when the call works fine, once when it drops. Compare the two outputs. If a specific hop shows clean latency in the morning but spikes in the evening, that is network congestion at that point. If it is on your ISP's network (hops 2–4), they are oversubscribed. If it is further out (hops 5+), it is a peering or backbone issue.

Scenario 3: One Website Is Slow but Everything Else Is Fine

Traceroute to the slow website. If the first few hops (your ISP) look clean but latency spikes once you hit the destination's network, the problem is on their end — not yours. You can use this information to file a useful support ticket with the website's hosting provider, or simply confirm that the issue is outside your control.

Scenario 4: High Latency at Hop 1

If hop 1 (your own router) shows latency above 5 ms, the problem is inside your home network. Common causes: Wi-Fi interference (switch to Ethernet to test), an overloaded router (too many connected devices or active streams), or old firmware on your router. This is the one scenario where the traceroute tells you the fix is entirely in your hands.

Common Mistakes When Reading Traceroute Results

• Panicking about asterisks — A single row of * almost always means the router blocks ICMP, not that the route is broken. Only worry if asterisks persist through the end of the trace.
• Blaming a single high-latency hop — If hop 8 shows 150 ms but hop 9 is back to 35 ms, hop 8 is just slow at replying to traceroute probes. The traffic itself is flowing fine.
• Running only one traceroute — Network conditions change constantly. Run multiple traces at different times to identify consistent vs. intermittent issues.
• Ignoring the three RTT columns — The spread between the three values matters. Consistent values (18, 19, 18 ms) mean a stable hop. Wildly varying values (12, 145, 18 ms) indicate jitter, which destroys real-time applications.
• Not comparing to a known-good destination — Always run a traceroute to a reliable reference (like 8.8.8.8 or 1.1.1.1) alongside your problem destination. This separates issues on your ISP's side from issues on the destination's side.

Advanced Traceroute Tips

Use MTR for Continuous Monitoring

MTR (My Traceroute) combines traceroute and ping into a single tool that continuously updates. Instead of a snapshot, MTR gives you a live view showing packet loss percentage, average latency, and jitter at every hop over time. On Linux and macOS, install it via your package manager (brew install mtr or apt install mtr). On Windows, use WinMTR — a free graphical version.

Traceroute Both Directions

Internet routing is asymmetric — the path from you to a server is often different from the path back. A traceroute from your computer only shows the outbound path. To see the return path, use a looking glass tool or Pong.com's traceroute, which runs from our servers. Comparing both directions is essential when diagnosing one-way packet loss or asymmetric latency.

Target the Right Destination

Do not just traceroute to "google.com." Traceroute to the specific server causing problems — the game server IP, the Zoom media relay, or the CDN edge your streaming service uses. Different destinations take completely different paths through the internet, even from the same source.

Frequently Asked Questions

The Bottom Line

A speed test tells you how fast. A traceroute tells you where and why. When your internet has problems that a speed test cannot explain — gaming lag despite good bandwidth, video calls that drop at the same time every day, one website that loads slowly while everything else is fine — a traceroute is the tool that turns vague frustration into specific, actionable information.

Run your speed test on Pong.com first to get the big picture. If the results look off, follow up with our free traceroute tool to pinpoint exactly where the problem lives. Armed with that data, you can have a very different conversation with your ISP — one that gets results.