MACROMEDIA COLDFUSION MX-CLUSTERCATS Use Manual page 29

The following figure shows these concepts:
DNS servers store information about the domain name space and are referred to as name
servers. Name servers typically have one or more zones for which they are responsible.
The name server has authority for those zones and is aware of all the other DNS name
servers that are in the same domain.
DNS record types, server aliases, and round-robin distribution
There are three DNS record types that you must define and configure for each web server
in order for ClusterCATS load-balancing and failover technology to work correctly.
These records must be defined and configured on your local and primary DNS servers.
A Record — contains a host-name-to-IP-address mapping, where the natural
language name is the primary name representing the IP address.
PTR Record — contains the IP-address-to-host-name mapping. This is the reverse
lookup of the A record, in which, given the IP address, the natural language host
name for the IP address is displayed.
CNAME Record — short for canonical record. This record contains an alias name
that maps to the primary host name of a web server. For example, you can assign a
server named www1.yourcompany.com an alias of www.yourcompany.com, so that
users never see www1.yourcompany.com, in the event of a server redirection.
To see how all of these records work together, let's look at a simple example. There are
two web servers, named www1.yourcompany.com and www2.yourcompany.com. You
don't want users to see the primary host names (A records) for these servers in their
browser; you want them to see only their assigned aliases (CNAME records), when being
redirected.
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