System Administration Guide: Network Services

sendmail and Name Services

sendmail imposes various requirements on name services. To improve your understanding of these requirements, this section first describes the relationship of mail domains to name service domains. Then the section describes the various requirements. Refer to the following.

Mail Domains and Name Service Domains

The mail domain name must be a suffix of the name service domain. For example, if the domain name of the name service is A.B.C.D, the mail domain name could be one of the following.

When first established, the mail domain name is often identical to the name service domain. As the network grows, the name service domain can be divided into smaller pieces to make the name service more manageable. However, the mail domain often remains undivided to provide consistent aliasing.

Requirements for Name Services

This section describes the requirements that sendmail imposes on name services.

A host table or map in a name service must be set up to support three types of gethostbyname() queries.

Two additional rules about the host name service need to be followed to establish efficient sendmail services within a name service.

For more information about the gethostbyname() function, refer to the gethostbyname(3NSL) man page.