What are A (Address) Records?
A. Name: This will be the host name for the record, typically a computer or server within your domain. It is important to note, the domain name is automatically appended to the “Name” field of the record. For example, defining www.example.com in DNS would be creating an A record with the name field of “www” within the example.com domain. If the “Name” field is left blank, it represents the root record of the domain. The root record for the domain can also be referred to as the “apex” record or represented with an “@” symbol in some documentation.
B. IP: The IPv4 address of the FQDN. An IP (Internet Protocol) address consists of a four octet 32-bit address.
TTL: The TTL (Time to Live) in seconds is the amount of time the record will cache in resolving name servers and in web browsers. The longer the TTL, the less frequent remote systems will lookup the DNS record, and the less query traffic the domain receives. The shorter the TTL, the faster DNS changes propagate in servers that have cached data, and the higher the volume of query traffic the domain receives.
C. TTL Recommended values:
Records configured with dynamic IP’s or Failover should have TTL’s set anywhere from 180 to 600 (3 to 10 minutes cache).
Records that are static should have TTL’s set between 1800 (being on the low end) to 86400 seconds (30 minutes to 1 day cache).
If a change is needed for a record with a high TTL, the TTL can be lowered prior to making the change and then raised back up again after.