dnsbench

A simple CLI tool to benchmark DNS resolvers against a list of domains, measuring latency and success rate, and producing reports in multiple formats (CSV, table, JSON).

Now ships with an embedded Web UI dashboard for live monitoring and control.

Features

• Built-in list of major, privacy-focused, regional, and alternative DNS resolvers
• Option to supply custom resolvers (-f resolvers.txt)
• Default popular domains list; can supply your own (-s domains.txt)
• Configurable number of repeats per domain (-n)
• Configurable per-query timeout (-t)
• Adjustable concurrency (-c)
• Multiple output formats: default, table, CSV, and JSON for integration with other tools
• Configurable logging levels (default, verbose, disabled)
• Warmup runs: Optionally perform warmup queries before benchmarking to reduce cold-start effects (--warmup N)
• Embedded Web UI dashboard (-ui) with live SSE updates, configurable domains/resolvers, and result tables

Installation

Build locally (requires Go 1.24+):

git clone https://github.com/handsomefox/dnsbench.git
cd dnsbench
go mod tidy
make build

Or install directly:

go install github.com/handsomefox/dnsbench@latest

Usage

# Recommended
./dnsbench -log=disabled -c=8 -n=5 -major=true -output=table -warmup=2

# More repeats, longer timeout
./dnsbench -n 20 -t 5s

# Output results in CSV format
./dnsbench -output csv

# Output as a simple table
./dnsbench -output table

# Output as JSON
./dnsbench --output json > results.json

# Disable logging
./dnsbench -log disabled

# Verbose logging with CSV output
./dnsbench -log verbose -output csv

# Custom resolvers list, custom concurrency
./dnsbench -f myresolvers.txt -c 8

# Custom domains list
./dnsbench -s mydomains.txt

# Only benchmark major resolvers
./dnsbench -major

# Perform 3 warmup queries per resolver/domain before benchmarking
./dnsbench --warmup 3

# Start the Web UI dashboard on port 8080
./dnsbench -ui -listen :8080

Flags

• -f string Optional file with resolvers (name;ip per line)
• -s string Optional file with domains (one domain per line)
• -n int Number of times each domain is queried
• -t duration Timeout per DNS query (e.g. 1500ms, 2s)
• -c int Maximum concurrent DNS queries
• -output string Output format: "default", "csv", "table", or "json"
• -log string Logging level: "default", "verbose", or "disabled"
• -major Benchmark only major DNS resolvers
• --warmup int Number of warmup queries per resolver/domain before benchmarking
• -ui Start the embedded Web UI server instead of running the CLI benchmark
• -listen string Address for the Web UI server (default :8080)

Example JSON Output Structure

{
  "results": [
    {
      "server": { "name": "Cloudflare-1", "addr": "1.1.1.1" },
      "stats": { "min": 12.3, "max": 25.6, "mean": 15.2, "count": 10, "errors": 0, "total": 10 },
      "per_domain_stats": {
        "google.com": { "min": 12.3, ... },
        "github.com": { ... }
      }
    },
    ...
  ],
  "summary": {
    "fastest_resolver": "Cloudflare-1",
    "slowest_resolver": "SomeDNS",
    "overall_success_rate": 0.98,
    ...
  }
}

Makefile

• make build – build UI, run tests, compile host binary
• make build-windows - build UI, run tests, compile Windows binary
• make run – build and run CLI with defaults (N/TIMEOUT overridable)
• make run-ui – build everything then launch the Web UI at http://localhost:8080
• make ui-install – install front-end dependencies
• make ui-build – build the static Web UI (Vite)
• make ui-dev – start the Vite dev server for UI work

License

This project is licensed under the MIT License. See LICENSE for details.