MACROMEDIA COLDFUSION MX-CLUSTERCATS Use Manual page 45

The primary DNS server contains tables of forward and reverse name translations. For
example, forward translation entries (A records) look like this:
www1.company.com
www2.company.com
Reverse translation entries (PTR records) are opposite, and look like this:
192.168.0.1
192.168.0.2
Configure your websites with forward and reverse DNS entries on your primary DNS
server. If you are not responsible for maintaining your primary DNS server, tell your
DNS administrator to add forward and reverse entries for your explicit web server names
(www1.company.com, www2.company.com, and so on).
Note: ClusterCATS does not operate correctly unless both forward and reverse
translations are configured for each explicit web server.
Local DNS servers
A local DNS server usually resides at a web hosting facility. The local DNS server stores
its own local table of name translations for the websites that the browser visits. If a user
enters a URL in a browser that the browser has already visited, it retrieves the host
name-to-IP address translation from the local DNS server's table. However, if a user
enters a URL for a site that the browser on that computer has never visited, the local
DNS server must access the primary DNS server on the Internet to resolve the
name-to-IP mapping before the browser can send a request to the appropriate web server.
To summarize, primary and local DNS servers work together to resolve name-to-IP
address mappings in the following way:
1 A user enters a website URL in a browser.
2 The browser checks the local DNS server for the name-to-IP address mapping. This
server typically resides at the facility where the web servers are hosted.
3 If the local DNS server does not have the mapping, it goes to the Internet and locates
the primary DNS server to look up the name-to-IP address mapping.
If round-robin DNS is in use, the primary DNS server determines which server in
the cluster is next in line to receive the request.
4 The primary DNS server sends the translation to the local DNS server, which in turn
sends it to the user's browser.
5 The browser sends an HTTP request to the correct web server hosting the site.
192.168.0.1
192.168.0.2
www1.company.com
www2.company.com
Before you install 35