Check out example codes for "dns ttl meaning". It will help you in understanding the concepts better.
Code Example 1
/** DNS TTL (time to live) is a setting that tells the DNS resolver how long to cache a query before requesting a new one. The information gathered is then stored in the cache of the recursive or local resolver for the TTL before it reaches back out to collect new, updated details. **/
Learn ReactJs, React Native from akashmittal.com