tool / latency
TCP Latency
TCP connect time to a host and port.
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About TCP Latency
- 01 / What
- This times the TCP handshake from our edge to the host, not a multi-region average.
- 02 / How to use
- 1. Enter a domain. 2. Read the response time. 3. Repeat a few times, since one result can vary.
- 03 / Good to know
- One location only. Results will differ from where your visitors are.
Questions about tcp latency test
Is this a ping?+
It measures TCP connect time, not ICMP ping.
Why do results vary?+
Network load and caching change each run.
Does it test from many countries?+
No. One edge location.
Guides and comparisons
Tool Details & Usage
Information on inputs, outputs, and limitations.
Overview
Opens five TCP connections in a row to a host and port and times each handshake. No data is sent after the connection opens.
Inputs
- Target: Domain or public IP. Private and internal addresses are refused.
Output Interpretation
- Latency: Average handshake time over the successful tries. Slowest is the worst of the five.
- Status: ONLINE if at least one connection opened, UNREACHABLE if none did within 3 seconds.
Examples & Limitations
- Example Use Case: Checking whether a server answers on port 443 and how quickly.
- Limitation: Measured from the Cloudflare edge that runs the request, not from your device or from several regions. The web tool tests port 443; the API accepts a few common ports through the
portparameter.
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