A record
A records are configured on a DNS server. A records indicate the IP address to which a host name resolves. In their most simple form, A records use the following format:
mail IN A 192.168.1.10
where:
• mail is the name of the host
• IN indicates the Internet protocol class
• A indicates that the DNS resource record is of the IPv4 address type
• 192.168.1.10 indicates the IP address that hosts the domain name
When an email client sends an email, the sender’s MTA queries a DNS server for the MX record of the domain name in the recipient’s email address. To resolve the host name of the MTA referenced by the MX record, it then queries for the A record of the destination MTA. That A record provides the IP address of the email server or gateway. The sender’s MTA then attempts to deliver the email to that IP address.
You must configure the public DNS server for your host names with an A record to resolve the host names referenced in MX records, and the host name of the FortiMail unit, if any. For example, if an MX record is:
example.com IN MX 10 fortimail.example.com
the required A record in the example.com zone file might be:
fortimail IN A 192.168.1.15