What Happens Between Typing a Domain and the Page Loading
Typing a domain starts a lookup, not a connection. The resolver is asked for the address behind the name, and if it does not already know it, it asks a chain of servers, root, then the top-level domain, then the domain's own nameservers, until one returns an address the browser can connect to.
Caching is what makes that chain invisible most of the time, and it is also what makes DNS problems so confusing to diagnose. A record changed an hour ago may be live for one user, stale for another, and correct on a phone but not on a laptop, purely because different resolvers cached it at different moments. What does not belong on screen is your own zone data: record values, internal hostnames, and registrar details should stay in the runbook rather than in a module that circulates.
The lookup runs across seven scenes: one on names against addresses, two following one query up the chain, one on caching and time to live, one on the record types first-line support actually meets, one on why propagation is a caching effect rather than a transfer, and one on the three checks that identify a DNS fault.
