What is caching in DNS and why is it important?

• A. DNS caching stores previously resolved domain names to speed up future lookups and reduce query traffic.
• B. DNS caching stores previously resolved domain names to speed up future lookups.
• C. DNS caching blocks suspicious domains to protect users.
• D. DNS caching ensures real-time updates for all DNS records.

Answer: (A)

DNS caching stores the answers from previous domain-name lookups so a resolver can answer future requests for the same domain immediately from its memory instead of querying authoritative servers again. This speeds up the user’s experience by reducing latency and also lowers overall traffic on DNS infrastructure because fewer queries travel across the network.

A key detail is the time-to-live (TTL) value that accompanies cached records. TTL tells how long a cached answer can be reused before the resolver must check for an updated result. This balance keeps performance high while still allowing updates to propagate eventually. That’s why the option that mentions both speeding up lookups and reducing query traffic is the best description.

Caching isn’t about blocking suspicious domains—that’s a security feature handled by other systems—and it doesn’t guarantee real-time updates, since cached data may be reused until its TTL expires.