Adding a DNS zone

The first step you need to take in setting up DNS on the hosting appliance is to configure the zones that will contain the DNS host records. There are different types of zones you can create, including forward or reverse DNS zones and master or slave DNS zones.

Forward vs. reverse DNS zones

Most requests for name resolution are "forward" requests, where a domain name (such as xyzcorp.com) is supplied to the DNS server with a request for its corresponding IP address. In order for the hosting appliance to resolve these forward DNS requests, a DNS zone must be created and contain forward DNS host records for the domain. On occasion, clients may need to supply an IP address (or IP subnet) and request its corresponding domain name. A reverse zone must be configured and contain reverse DNS host records to resolve this type of DNS request.

Master vs. slave zones

DNS is a distributed database that can reside on multiple servers to eliminate downtime risk due to a single failure point. In this distributed database there are master (or primary) servers and slave (or secondary) servers.

A master server is the main server that keeps the primary copy of the DNS database in its memory and on disk. A slave server obtains a copy of the database from the master server and serves as a backup to the master DNS server. Periodic updates from the master server refresh the slave server's copy of the DNS database. When a zone is modified, all hosts listed in slave server records are notified of the changes to maintain synchronization between the master zone and all slave zones. An active zone can be switched from master to slave, or from slave to master. (Configuring a slave of another slave is not suported.) When a slave zone is promoted to a master, the latest known data is used as the primary source.

To add a DNS zone
  1. In the left menu, click DNS.

  2. Click Add Forward or Add Reverse depending on the type of zone you need to create.

  3. On the Add Forward/Reverse DNS Zone page, configure the zone options shown in the following table, then click Add.

Option

Description

DNS zone name

The name of the DNS zone. This is usually the domain name you have registered with a DNS registrar, or a domain name provided by your network administrator.

Master/slave zone

This option enables you specify whether this zone functions as a master or slave for its data.

IP address

This is usually the IP address for the corresponding virtual domain that is hosted on this server. If you use a different server to host your Web site for this domain, enter that server's IP address instead.

Administrator e-mail

This is the e-mail address of the person assigned to maintain the DNS database for this zone (provided for reference purposes only).

Refresh after

Specifies how frequently the clients update their cache with new DNS entries from the server.

Retry after

Specifies how long the clients will wait to update from the server.

Expire after

Specifies when the zone data in the DNS cache expires.

Minimum TTL

The minimum "time to live" for record data in the client cache.

Master server name

For every slave zone, you need to specify the name of a master server that will serve as the authoritative data source.