If a DNS record's TTL expires, what happens?

• A. A fresh DNS lookup will be performed to obtain updated information.
• B. The DNS record becomes permanently invalid.
• C. The browser will never query DNS again for that domain.
• D. The server will automatically revoke the domain name.

Answer: (A)

TTL, or Time To Live, is the duration that a DNS answer can be stored in a cache before it is considered stale. When that time runs out, the cached record is discarded and the next time a client looks up the domain, the resolver performs a fresh DNS query to obtain current information from the authoritative servers. This ensures that changes to DNS data can propagate over time while still letting lookups be fast most of the time. So, after TTL expires, you’ll get a new lookup to refresh the data, rather than using the old cached answer. It doesn’t permanently invalidate the record, it doesn’t prevent future queries, and it doesn’t revoke domain names.