I'm trying to figure out what the DNS settings should be for a multiple server installation so I can get it right on the first try. All the instructions I see indicate I need an A and MX record for "the" server, but that's not much help when I'm working with three servers (LDAP, Mailbox, and MTA). Which is "the" server? From what I can tell the mailbox server seems to be running all the services (webmail, admin, IMAP, POP, etc) so I should point my A record there, but what about my MX record? Shouldn't that be pointing to the MTA server? And what if I add more Mailbox servers? Do I need multiple sub-domains? But then won't I need multiple certificates? The installation guide doesn't give me much to go on here. It's all incredibly foggy and I could really use some clarification.
Edit: For example, say this is my configuration.DNS Configuration Requirement
In order to send and receive email, the Zimbra MTA must be configured in DNS with both A and MX records. For sending mail, the MTA uses DNS to resolve hostnames and email-routing information. To receive mail the MX record must be configured correctly to route the message to the mail server.
During the installation process ZCS checks to see if you have an MX record correctly configured. If it is not, an error is displayed suggesting that the domain name have an MX record configured in DNS.
You must configure a relay host if you do not enable DNS. After ZCS is installed, go to the Global Settings>MTA tab on the administration console and uncheck Enable DNS lookups. Enter the relay MTA address to use for external delivery.
Note: Even if a relay host is configured, an MX record is still required if the ZCS server is going to receive email from the internet.
Domain: mydomain.com (firstname.lastname@example.org)
A - mydomain.com -> maibox.mynetwork.com
MX - mydomain.com -> mta.mynetwork.com
mydomain.com installed on maibox.mynetwork.com
Would that be correct? It seems like something's missing to me...