If a website works for some visitors but not others, first determine whether the difference follows DNS caching, browser caching, network path, or the client itself.
- Test the hostname with more than one DNS resolver and compare the returned addresses.
- Confirm the domain is delegated to the intended authoritative nameservers.
- If DNS changed recently, remember that cached records can remain until their TTL expires; nameserver changes can take longer to become consistent across recursive resolvers.
- Test in a private browser window and clear local DNS/browser caches where appropriate.
- Compare HTTP and HTTPS behavior and check whether one hostname, such as
www, points somewhere different from the root domain.
If every resolver points to the same server but only certain networks fail, the problem may be outside the website application itself. Avoid repeatedly changing DNS while caches are still converging.
