Names to addresses.
WHAT IT IS
The system translating names people use into addresses machines use.
WHY IT EXISTS
Nobody remembers addresses.
WHAT HAPPENS WHEN YOU ENTER A NAME
Your device checks its own cache Then asks a resolver, usually your provider's or one you configured The resolver asks the authoritative servers for that name The answer returns and is cached
WHY CACHING EXISTS
Efficiency. Asking every time would be slow.
WHAT CACHING CAUSES
Changes not appearing immediately.
WHAT AUTHORITATIVE MEANS
The servers holding the actual records for a name.
Whoever controls those controls where the name points.
WHY THAT MATTERS
Changing nameservers changes which servers are authoritative.
Records must exist wherever authority sits.
WHAT FAILS MOST OFTEN
Records missing at the authoritative servers Nameservers pointing somewhere unexpected Caching hiding a change that has been made
