What Is Traceroute and How to Use It

Published March 4, 2026 · 7 min read

When you visit a website or stream a video, your data doesn't travel directly from your device to the server. It hops through a series of routers across the internet, each one forwarding your packets closer to the destination. Traceroute lets you see every one of those hops — and that's incredibly useful for diagnosing network problems.

How Traceroute Works

Traceroute exploits a clever trick with a network protocol feature called TTL (Time to Live). Every packet sent across the internet has a TTL value — a counter that decreases by one at each router. When a router receives a packet with TTL of 1, it discards the packet and sends back an error message saying "time exceeded."

Traceroute uses this behavior deliberately:

1. It sends a packet with TTL = 1. The first router drops it and reports back. Now you know the first hop.
2. It sends a packet with TTL = 2. The second router drops it. Now you know the second hop.
3. It keeps increasing TTL until the packet reaches the destination.

At each step, traceroute records the IP address of the router that responded and how long the round trip took. The result is a complete map of the route your data takes.

Reading Traceroute Output

A typical traceroute result looks something like this:

Each line represents one hop along the route:

• Hop number — The position in the route (1 is your local router)
• Host — The IP address (and sometimes hostname) of the router
• RTT — Round Trip Time, how long it took for the packet to reach that hop and the response to come back

What the Hops Tell You

Hop 1 is almost always your home router. If you see high latency here, the problem is on your local network — WiFi interference, a congested router, or a bad cable.

Hops 2-3 are typically your ISP's network. High latency or packet loss here suggests an issue with your internet provider.

Middle hops are transit networks — the backbone infrastructure that carries data across the internet. These are managed by major carriers like Cogent, Level 3, or Telia.

Final hops are the destination network. If latency jumps dramatically only at the last hop, the server itself may be overloaded.

Common Patterns and What They Mean

Latency Spike at One Hop

If the RTT suddenly jumps at hop 4 and stays high for all subsequent hops, the problem is at hop 4 or between hop 3 and 4. This is the most common and useful diagnosis traceroute provides.

Asterisks (* * *)

If you see asterisks instead of times, it means that router didn't respond. This is often normal — many routers are configured to ignore traceroute packets to reduce load. If the trace completes successfully at the end, these timeouts are harmless.

Increasing Latency Throughout

Gradually increasing latency is normal, especially for destinations on other continents. Light travels through fiber at about 200,000 km/s, so physical distance adds real delay. A route from New York to Tokyo will naturally have 150+ ms of latency.

Looping Hops

If you see the same IP addresses repeating, there may be a routing loop. This is rare but serious — it means packets are being passed back and forth between routers without making progress. Routing loops usually resolve themselves within minutes as routing protocols converge.

Traceroute vs. MTR

Standard traceroute runs once and gives you a snapshot. But network conditions fluctuate. A single traceroute might miss intermittent packet loss or show a latency spike that was just a momentary blip.

MTR (My Traceroute) solves this by running continuously. It combines traceroute with ping, repeatedly probing each hop and accumulating statistics over time:

• Packet loss % — Shows reliability at each hop. Even 1-2% loss can degrade performance.
• Average latency — More reliable than a single measurement
• Best/worst RTT — Shows the range of latency you're experiencing
• Standard deviation — High jitter indicates an unstable connection

If you're reporting a network issue to your ISP, an MTR report is far more convincing than a single traceroute. It shows sustained problems rather than momentary ones.

Using Traceroute on iPhone

PingKit provides both Visual Traceroute and MTR directly on your iPhone:

Visual Traceroute plots each hop on an interactive map, showing you the geographic path your data takes. It resolves IP addresses to locations and shows you exactly where your packets travel — sometimes through unexpected countries.

MTR runs continuously in the background, building up statistics over time. You can run it for 30 seconds or 5 minutes to get a clear picture of connection quality to any host.

When to Use Traceroute

• Slow website? — Traceroute shows where the delay is happening
• Gaming lag? — Find the hop with the highest latency
• ISP issues? — An MTR report gives your ISP the data they need to fix the problem
• Choosing a VPN server? — Traceroute to different servers to find the fastest route
• Understanding your network? — See how your traffic actually flows across the internet

Tips for Better Diagnoses

1. Run traceroute to the same destination multiple times at different times of day. Network conditions change.
2. Use MTR for at least 60 seconds to get reliable statistics. Short runs may not capture intermittent issues.
3. Compare to a known-good destination like 8.8.8.8 (Google DNS). If that's fast but your target is slow, the problem is likely on the destination's end.
4. Focus on where latency increases, not absolute values. Each hop adds some latency — that's normal. Look for unusual jumps.
5. Don't worry about unresponsive hops (asterisks) in the middle if the final destination responds normally.