GENERAL KNOWLEDGE

Detailed explanation-1: -Generally, we recommend a TTL of 24 hours (86, 400 seconds). However, if you are planning to make DNS changes, you should lower the TTL to 5 minutes (300 seconds) at least 24 hours in advance of making the changes. After the changes are made, increase the TTL back to 24 hours.

Detailed explanation-2: -With a TTL of 3600 seconds, or 1 hour, that means that as a recursive server learns about example.com, it will store that information about the A-record at example.com for one hour.