Which statement about DNS caching TTL is true?

• A. TTL defines how long a DNS record may be cached by a resolver
• B. TTL defines the time to lease for domain
• C. TTL defines the time to locale
• D. TTL defines the last update time

Answer: (A)

TTL, or time-to-live, is the duration a DNS resolver can keep a cached DNS response before it must fetch a fresh copy. This value is carried with the DNS answer and tells the resolver how long it can serve the cached result. If the same query comes in before the TTL expires, the resolver can answer from its cache, speeding things up and reducing network traffic. Once the TTL expires, the resolver must re-query the authoritative server to get the latest information, allowing any changes in the DNS records to propagate. TTLs are set per DNS record in the zone file and can impact how quickly updates are visible—shorter TTLs allow faster changes but increase query load, while longer TTLs reduce load but delay propagation. The other options describe concepts that aren’t about how long DNS results are cached.