MACROMEDIA COLDFUSION 4.5-ADMINISTRING COLDFUSION..., Manual

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Chapter 6: Creating Scalable and Highly Available Web Sites 171
To configure DNS records on your UNIX-based DNS server
See the operating system documentation that came with your UNIX server for specific
procedures about how to define DNS records on your UNIX-based DNS server.
Configure your Web server’s network settings
Successful clustering depends highly on whether you’ve configured your Web server’s
network settings properly. To understand how specific network configurations affect
clustering, let’s review important server failover concepts.
ClusterCATS uses an “IP keep alive” strategy to accomplish transparent server failover
when a Web server fails. This process involves each server in the cluster listening for an
IP signal from each server. If a server stops emitting the signal, ClusterCATS assumes
there is a problem with the server and restricts it from processing any additional
requests. The least loaded available server in the cluster assumes the IP address of the
restricted server, and all subsequent requests are redirected to the failover server until
the restricted server’s problems are fixed. This process of moving a Web site IP address
from one server to another in the cluster is known as dynamic addressing.