Response Time Checker / Glossary
DNS lookup
The time to turn the hostname into an IP address. A visitor whose resolver has the answer cached pays almost nothing; a first visit pays the full lookup, including every CNAME along the way.
How we measure it
Our probe resolves the name fresh for every sample through the system resolver and records the time to the answer.
What good looks like
Under 50 ms is typical for a well-run anycast DNS provider; we flag lookups over 100 ms (median).
How to improve it
- Use an anycast DNS provider.
- Shorten CNAME chains (each link is another lookup).
- Keep TTLs reasonable so resolvers can cache the answer.
Measure your site
Three cold samples, every phase, and a diagnosis of what is slow.
Open the Response Time Checker