Chapter 4. DNS and Postfix
One of the most important yet misunderstood aspects of an e-mail system is the use of hostnames. It is crucial to ensure that hostnames are defined properly in order for mail systems to communicate. Postfix is no different.
The domain name system (DNS) was developed to allow systems to communicate using a hierarchy of hostnames instead of the native IP numbering scheme. DNS also identifies servers that provide special services for domains, such as e-mail. This is where DNS becomes crucial for e-mail servers.
Although knowledge of DNS isn't essential for installing and configuring Postfix, it certainly helps when you are trying to troubleshoot mail problems. At some point in your mail administration career, you will most ...