The ghost domain problem in DNS, and what we're doing about it
Summary
The ghost domain problem in DNS describes how a domain removed from registry control can remain resolvable by caches, causing false uptime results. Oh Dear explains how this happens across registries and resolvers, and details their mitigation: using a local recursive resolver with tighter caches, enabling hardened referral paths, and experimenting with DNSSEC validation. The post also situates the issue within the broader practice of DNS and uptime monitoring and outlines planned and potential fixes.