Configuring and Managing MPE/iX Internet Services (August 2002)

Chapter 8
DNS BIND/iX
Data Files
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The number (10 in this case) in the fourth field represents a preference value. If you define multiple MX
records for a host, delivery is attempted to lower-preference value hosts first. The actual value isn’t
important, only its relationship to other preference values.
On larger LANs it’s a good idea to create backup e-mail servers. Smaller LANs can simply rely on the fact
that most SMTP mailers will retry deliveries to the site for three days before returning a message to its
sender.
The line, shown commented out here, would arrange to redirect e-mail for all hosts in this domain to a single
machine:
;
; All mail for net delivered to nova
;
;* IN MX 10 nova.maxx.net.
This is a very good idea for LANs that benefit from a central e-mail repository.