One of the advantages of the Domain Name System over host
tables is its support of advanced mail routing. DNS offers a mechanism
for specifying backup hosts for mail delivery. The mechanism also
allows hosts to assume mail handling responsibilities for other
hosts. This lets diskless workstations that don't run mailers,
for example, have mail addressed to them processed by their server.
These features give administrators more flexibility in configuring
electronic mail on their network.
MX Records |
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DNS uses a single type of resource record to implement enhanced
mail routing, the MX record. MX records specify a mail exchanger
for a domain name, a host that will either process or forward mail
for the domain name.
In order to prevent mail routing loops, the MX record has
an extra parameter, besides the domain name of the mail exchanger,
a preference value like: peets.mpk.ca.us IN MX 10 relay.hp.com
specifies that relay.hp.com is
a mail exchanger for peets.mpk.ca.us
at preference value 10.
