Online Traceroute

What is Online Traceroute?

Traceroute is a network diagnostic utility that maps the path packets take from a source host to a destination, revealing each intermediate router (hop) along the way. Each hop represents a hand-off between network segments — typically from your ISP to a tier-1 backbone provider, through regional peering points, and finally to the destination network's edge.

Traditional traceroute works by sending packets with increasing TTL (Time To Live) values. When a router receives a packet with TTL=1, it discards the packet and sends an ICMP Time Exceeded message back to the sender. By incrementing the TTL by one each round, the tool collects responses from each successive hop and builds a complete route map with per-hop latency.

Online traceroute tools — including this one — cannot send raw ICMP packets because browsers and serverless environments do not have operating-system-level socket access. Instead, this tool approximates the route by measuring HTTP HEAD response latency at multiple timeout thresholds, then infers intermediate hops from the timing distribution. Hops marked "estimated" are inferred, not directly observed. For exact ICMP hop data, use the CLI equivalents shown below.

How to Read Traceroute Output

Status	Meaning	Action
reached	The hop responded and latency was measured directly	Note latency; >200ms may indicate congested segment
estimated	Intermediate hop inferred from timing distribution	Use as directional indicator, not absolute measurement
filtered	Router is present but blocks ICMP Time Exceeded replies	Normal for many enterprise and CDN edge nodes
timeout	No response within timeout window — host may be unreachable	Check DNS, firewall rules, and try again from CLI
* * *	Three asterisks — standard notation for a non-responding hop	Continue past; final hop may still respond

Traceroute vs Ping — Key Differences

Ping and traceroute serve different diagnostic purposes. Ping sends ICMP Echo Request packets directly to the destination and reports whether the host is reachable and how long it takes to respond. It tells you if you can reach the destination but not why you cannot if the check fails.

Traceroute reveals the path to the destination. When a connection is slow or failing, traceroute shows you which specific hop is introducing latency or dropping packets. If hop 7 suddenly shows 300ms of latency while all earlier hops were under 20ms, that segment is the likely culprit — not the destination server.

Use ping when you need to confirm basic reachability and measure end-to-end RTT.
Use traceroute when you need to identify which network segment is causing high latency, packet loss, or routing anomalies.

CLI Reference — Exact ICMP Traceroute

For production-grade hop analysis, use these commands directly from your terminal:

Linux / macOS

traceroute example.com

Windows

tracert example.com

macOS (with AS lookup)

traceroute -a example.com

Linux (TCP mode — bypasses ICMP filters)

sudo traceroute -T -p 443 example.com

Common Issues and Resolutions

All hops show * * *

Cause: The target host or its upstream firewall blocks all ICMP Time Exceeded responses.

Fix: Use TCP traceroute: sudo traceroute -T -p 443 example.com. Also try ping to confirm the host is at least reachable at the HTTP layer.

Trace completes but final latency is very high

Cause: Geographic routing inefficiency, congested transit link, or the host is CDN-fronted but the origin is far from the Vercel edge.

Fix: Compare with traceroute from a different vantage (mtr on Linux). CDN tools like Fastly or Cloudflare analytics may explain origin distance.

Route looks correct but site still loads slowly

Cause: Network hops are fine, but origin server processing time (TTFB) is the bottleneck.

Fix: Use the HTTP Headers tool to inspect X-Cache and CF-Ray headers. Server-side profiling or a CDN upgrade typically helps here.

Estimated hops look wrong

Cause: Estimated hops are inferred from latency brackets, not direct ICMP probes — they can be inaccurate for complex routing topologies.

Fix: Use the CLI traceroute for accurate results. The online tool is best for quick first-pass diagnostics only.

Frequently Asked Questions

Why does online traceroute show fewer hops than my terminal?

Browser and serverless environments cannot send raw ICMP packets with controlled TTL values, which is the mechanism real traceroute uses. This tool approximates hops using HTTP HEAD latency at different timeout thresholds. Terminal traceroute sees every ICMP-responding router hop.

What does "estimated" mean in the hop status?

Estimated hops are inferred from the latency distribution across multiple HTTP probes. They indicate a likely intermediate network segment but are not directly confirmed by an ICMP Time Exceeded response as terminal traceroute would produce.

Why do many hops show * * * (no response)?

Many routers and firewalls are configured to drop ICMP Time Exceeded packets for security or performance reasons. This is normal, especially in corporate, CDN, and cloud environments. The final destination may still be reachable even if intermediate hops do not respond.

What is a good traceroute hop count?

Typical internet paths span 8–20 hops. Cross-continent routes (e.g., US to Asia) may reach 20–30 hops. More hops do not necessarily mean more latency — what matters is the latency at each hop, not the total count.

How is traceroute different from ping?

Ping tests if a host is reachable and measures end-to-end round-trip time. Traceroute maps every intermediate hop between you and the destination, which lets you pinpoint exactly where latency is introduced or packets are being dropped.