Apple 034-2351_Cvr manual Setting Up Namespace Behind a NAT Router

Step 2: Create records and priorities for the auxiliary mail servers

These instruction assume you have edited the original MX record. If not, please do so before proceeding.

These instructions also assume you have already set up and configured one or more auxiliary mail servers.

To enable backup or redundant mail servers:

1In Server Admin, select DNS in the Computers & Services pane.

2Click Settings.

3Select the Zones tab.

4Select the Zone you want to use.

5Click the Add button under the Records pane.

6Choose MX from the Type pop-up menu.

7Enter the domain name (like ‘example.com.’) in the From field.

8Enter the name of the mail server (like ‘backup.example.com.’) in the To field.

9Enter a precedence number for that server which is higher than that of the primary server.

A higher the number indicates it will be chosen if the primary server is unavailable.

10Click OK.

Setting Up Namespace Behind a NAT Router

If you’re behind a Network Address Translation (NAT) router, you have a special set of IP addresses that are only usable within the NAT environment. If you were to assign a domain name to these addresses outside of the NAT router, none of your domain names would resolve to the correct computer. See Chapter 4, “NAT Service,” on page 67 for more information about NAT.

You can, however, run a DNS service behind the router, assigning host names to the NAT IP addresses. This way, if you’re behind the NAT router, you can enter domain names rather than IP addresses to access servers, services, and workstations. Your DNS server should also have a Forwarding zone to send DNS requests outside of the NAT router to allow resolution of names outside the routed area. Your clients’ networking settings should specify the DNS server behind the NAT router. The process of setting up one of these networks is the same as setting up a private network. See “Setting Up a Private TCP/IP Network” on page 36 for more information.

If you choose to do this, names entered by users outside the NAT router won’t resolve to the addresses behind it. You should set the DNS records outside the NAT-routed area to point to the NAT router, and use NAT port forwarding to access computers behind the NAT router. For more information on port forwarding, see Chapter 4, “NAT Service,” on page 67.

Chapter 2 DNS Service

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