DNS and Mail
In our earlier example, in the section on SMTP, we managed to telnet to port 25 on the MTA and send some mail. This was easily accomplished, as we knew the name of the machine that we wanted to connect to.
However, if we are sending mail to a different domain, we need to locate the name of the machine that handles mail for the domain; that is, the MTA. Once we know this, we can connect to it and perform the same task. To do this we use a DNS lookup, which will search for the domain's Mail Exchange (MX) records. These records are used to indicate the mail server. For example, if we search for the MX records for Sun's domain, we may see something similar to the following:
hydrogen# nslookup Server: antimony.solarisbootcamp.com Address: ...
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