In order for your self-hosted external DNS server to service requests for a particular internet domain name, it is necessary to set up a forward lookup zone on the server for the domain to be serviced.
Creating the Zone
After logging on to the server, open the DNS management tool by clicking Start, Programs, Administrative Tools, DNS. Expand the top level of the tree in the left pane of the window, then click on Forward Lookup Zones. The currently configured zones will be listed in the right pane.
Installing the new zone file is a straightforward, wizard-driven process.
First, click Action, then New Zone. You can also right-click the Forward Lookup Zones entry in the tree, and select New Zone. Click Next on the first wizard step.
On the next step, ensure that Standard Primary is selected. A Primary DNS Server is one that is the primary authority for the zone database records for a particular zone. A Standard Primary DNS Server contains the “master” copy of the DNS zone database files. There can be only one Standard Primary DNS Server for a particular zone. Any other standard DNS Servers in a particular zone must be Secondary DNS Servers, which “pull” zone information from the primary.
The Standard Primary DNS Server plays a particularly important role on the network. Since it’s the only one that contains a writeable copy of the zone database file, all changes to the zone must be made on the Standard Primary DNS Server.
A Standard Primary DNS Server contains a Start of Authority record, which contains valuable information regarding how a zone should be transferred and aged. Only the Primary DNS Server contains this SOA record, indicating that the Standard Primary DNS Server is the “start” of the possible chain of authority for a particular zone.
After clicking the Next button on the Zone Type selection screen, you’ll be asked to enter a name for the zone. In the name field, enter the zone name only. Do not enter the names of any hosts or sub-domains in this field.
For example, if you are going to start processing requests for MyDomainName.com, you’d enter this in the name field.
Click Next to proceed with the wizard.
On the next screen, you’ll be asked how to set up the zone file. If you are creating a new zone file, which is most often the case, you can safely click next on this screen. However, if you have a pre-existing zone file, you can choose to import this file. This might be the case if you are performing a disaster recovery, or perhaps migrating from an old, retired server.
On the final screen, click Finish to complete the process. Your new forward lookup zone will appear at the bottom of the zone list in the right pane of the DNS manager.
Adding Host Records
You’ve created a new zone for an external domain name, but you’re not finished yet! You need to create some host records for the zone.
DNS records are stored in zone files and are used for translating domain names to IP addresses. They also contain other data, including the domain name’s name server and mail server information. If there are domain name aliases, such as the commonly used “www” preceding the domain name, these will also be listed in the DNS record.
Since DNS records are made up entirely of text, they are easy to modify when needed. However, one small typo could redirect a domain name to the wrong web server or prevent it from showing up at all. This is why it is important to enter DNS information accurately and double-check your changes entry before saving the zone file.
To create a new host record, click once on the zone name in the left pane, then select Action, and New Host. You can also right click in the zone name itself, and select New Host from the context menu.
In the name field of the New Host dialog, type the name of the host you want to be resolved from the internet. For example, if you want to let internet surfers access www.mydomainname.com, you’ll enter www in this field.
In the IP address field, enter the IP address of the actual server you want the request to go to. For example, if the IP address of the server that serves web pages for www.mydomainname.com is 64.233.161.147, you’d enter it in the IP address field here.
If you need to provide reverse DNS lookups for your host, be sure to place a check mark in the Create associated pointer (PTR) record checkbox. Finally, click Add Host. Your host entry is now in the zone file.
A Short Word on MX Records
When an e-mail message is sent through the Internet, the sending mail transfer agent makes a DNS query requesting the MX records for each recipient’s domain name, which is the portion of the e-mail address following the “@”. This query returns a list of host names of mail exchange servers accepting incoming mail for that domain, together with a preference number. The sending agent then attempts to establish an SMTP connection to one of these servers, starting with the one with the smallest preference number, delivering the message to the first server with which a connection can be made. If no MX records were present, the server falls back to A, that is to say, it makes a request for the A record of the same domain.
The MX mechanism provides the ability to run multiple mail servers for a single domain, and allows administrators to specify an order in which they should be tried. This ability to run multiple mail servers proves very valuable for high-availability clusters of inexpensive mail gateways, which can then process hundreds of messages per second in aggregate to quarantine or remove spam and/or viruses.
The MX mechanism does not grant the ability to provide mail service on alternative ports, nor does it provide the ability to distribute mail delivery across a set of equal-priority mail servers by assigning a weighting value to each one.
Adding an MX Record to the zone is similar to adding a standard host (A) record, with the added field of designating a priority for the MX record.