dnsbench

dnsbench measures how fast and how reliably DNS resolvers answer from your machine. It benchmarks one resolver at a time against a list of domains and reports latency and success rate as text, a table, CSV, or JSON. An embedded Web UI shows a run while it happens.

Build

You need Go 1.24.5 or later, Make, and Node.js. Vite 7 pins Node to 20.19.0 or later on the 20.x line, or to 22.12.0 and later.

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

make build builds the Web UI, runs the Go tests, and writes bin/dnsbench.

server.go embeds webui/dist/, and that directory is not committed, so plain go build and go test fail in a fresh checkout until the Web UI is built. go install github.com/handsomefox/dnsbench@latest fails for the same reason. Build through Make.

Run a benchmark

To test the built-in major resolvers with five lookups per domain, run:

./bin/dnsbench -major -n 5 -c 8 -warmup 2 -log disabled -output table

To test every built-in resolver with more repeats and a longer timeout, run:

./bin/dnsbench -n 20 -t 5s

The built-in resolver and domain lists are in data.go. Every flag, its default, and every report field is in the CLI reference.

Use your own resolvers and domains

Write resolvers.txt with one name;ip pair per line:

Cloudflare-1;1.1.1.1
Google-1;8.8.8.8

Write domains.txt with one domain per line:

github.com
google.com

Pass both files:

./bin/dnsbench -f resolvers.txt -s domains.txt -output table

Each file replaces the matching built-in list instead of adding to it, and -f overrides -major. For the validation rules, see input files.

Save a report

./bin/dnsbench -log disabled -output json > results.json
./bin/dnsbench -log disabled -output csv > results.csv

CSV writes the resolvers that answered to standard output and the ones that failed to standard error, so the redirect above captures only the successes. JSON puts both groups in one document, under results and failures.

One catch before you script against JSON. A resolver with no successful lookup gets NaN for its latencies, encoding/json refuses NaN, and dnsbench then writes failed to encode json results to standard error and produces no report at all. It still exits 0. See report formats.

Start the Web UI

./bin/dnsbench -ui -listen 127.0.0.1:8080

dnsbench tries to open your browser at that address. If it does not, open http://127.0.0.1:8080 yourself. Pick the domains, resolvers, and options, then click Start benchmark. Stop ends a run early, Reset clears the results, and View results switches to the results table.

-listen defaults to :8080, which accepts connections from anywhere that can reach your machine. The dashboard has no authentication, and it runs lookups against whatever resolver addresses a request names. If you expose it beyond your own machine, put it behind a firewall or a reverse proxy.

Documentation

• CLI reference: flags, lookup behavior, input files, and report formats.
• Web UI development: running and checking the dashboard.
• Contributing: build commands, conventions, and what to check.

dnsbench uses the MIT license.