When specifying TTL (Time To Live) values in DNS records, please be aware of the following important factors:

• The higher the TTL, the less frequently caching name servers need to query authoritative name servers.
  A higher TTL reduces the perceived latency of a site and decreases the dependency on the authoritative name servers.
  Beside this, a higher TTL makes harder a TTL Poisoning attack, so higher TTL is more secure too.

• The lower the TTL, the more frequently updates are propagated to other name servers.
  A slower TTL can make significantly slower your site. 

As standard, we recommend a TTL of 86,400 (24 hours), and not lower than 3,600 (1 hour).

If you are planning to make DNS changes, we recommend lowering the TTL at least 36 hours before making the changes.
So you should lower the TTL to 300 (5 minutes) at least 36 hours in advance of making the changes.
After the changes are made, increase the TTL back to 24 hours.

Minimum admitted TTL value is 300 (5 minutes).