PLANET CS-2000 - Manual (Page 474)

CS-2000 UTM Content Security Gateway User’s Manual
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3. MX
The MX can precede the mail transfer by the DNS search. If user want to change the mail server, then he
only need to modify the DNS record, in other words, the destination mail server has no need to know which
mail server that the user used to transfer mails.
Example 3：
The MX represents the mail exchange; it is a kind of DNS record used to provide the e-mail
service.
Host Name Type Address
host25.test.net.tw A 211.22.22.24
mail.test.net.tw MX host25.test.net.tw
The MX mapped relations
If we type nslookup -type=MX mail.test.net.tw in DOS . （ The nslookup is the DNS search command, and the
strings after -type represents the DNS record. The mail.test.net.tw is the searched DNS host name which
mapped to the host25.test.net.tw mail exchange and it also mapped to the IP address of 211.22.22.24.
We assume that test Customer Service Center sends the e-mail to [email protected] .
The Customer Service people send the mails through the test.com.tw (SMTP Server), and
the SMTP Server will ask mail.test.net.tw of which way to send mails via the DNS search.
The way to search the MX record in mail .test.net.tw.：
Host Name Type Address
host3.test.net.tw A 61.11.11.10
mail.test.net.tw MX host3.test.net.tw
The way to search the MX record in mail.test.net.tw
The mail server of mail.test.net.tw will send e-mails to the address of host3.test.net.tw via
SMTP Protocol.