In DNS resolution, TTL is used to do what?

In DNS resolution, TTL is used to do what?

• A. TTL determines how long a cached DNS answer remains valid.
• B. TTL has no impact on DNS caching.
• C. TTL determines the time to live for DNS server processes.
• D. TTL affects retransmission intervals for DNS responses.

Answer: (A)

TTL, or time to live, is the duration a DNS resolver should keep a DNS answer in its cache before considering it expired. The TTL value is attached to the DNS record and tells caches how long that information can be reused without refreshing. While the TTL is active, subsequent requests for the same name can be answered from cache, speeding up resolution and reducing queries to authoritative servers. Once the TTL expires, caches must fetch a fresh answer to ensure the data isn’t too stale. The TTL choice affects how quickly updates propagate versus how much traffic caching saves: short TTLs allow faster updates but generate more queries, while long TTLs reduce queries but may serve older information. It doesn’t set how long a DNS server process runs, nor does it determine retransmission timing for DNS messages.

TTL, or time to live, is the duration a DNS resolver should keep a DNS answer in its cache before considering it expired. The TTL value is attached to the DNS record and tells caches how long that information can be reused without refreshing. While the TTL is active, subsequent requests for the same name can be answered from cache, speeding up resolution and reducing queries to authoritative servers. Once the TTL expires, caches must fetch a fresh answer to ensure the data isn’t too stale. The TTL choice affects how quickly updates propagate versus how much traffic caching saves: short TTLs allow faster updates but generate more queries, while long TTLs reduce queries but may serve older information. It doesn’t set how long a DNS server process runs, nor does it determine retransmission timing for DNS messages.