Serving queries for clients.
WHAT A RESOLVER DOES
Accepts queries, performs resolution, caches answers, and returns them.
WHAT CACHING CONTROLS
How long an answer is retained, set by the record's time-to-live.
WHAT THAT MEANS FOR CHANGES
A change is not visible until cached copies expire.
WHAT PROPAGATION ACTUALLY IS
Caches expiring, not data spreading.
WHY THAT MATTERS
There is nothing to accelerate, and lowering the time-to-live in advance is the only preparation.
WHAT TO DO BEFORE A PLANNED CHANGE
Lower the value well ahead, change, then raise it once stable.
WHAT A RESOLVER MUST PROTECT AGAINST
Being used by anyone on the internet Cache poisoning Being used to amplify attacks
WHAT AN OPEN RESOLVER IS
One answering queries from anywhere.
WHY THAT IS DANGEROUS
It can be used to reflect and amplify traffic at a victim.
WHAT TO DO
Restrict recursion to your own networks.
WHAT RESPONSE RATE LIMITING DOES
Restricts repeated identical responses, reducing amplification value.
WHAT TO MONITOR
Query volume, failure rates, and unusual patterns.
