ClusterCATS clusters support DNS scheduling. With scheduling, you can have client URL requests redirected using DNS round robin to cycle the request through the servers in your round robin cluster. To do this, you create a global name in the DNS hierarchy at the desired level where the round robin name will reside.
For example, if you have three servers named: server1.sales.us.company.com, server2.sales.us.company.com, and server3.sales.us.company.com, you need a DNS object -- for example, www.sales.us.company.com, (or ussales.company.com) -- created at the appropriate level in DNS. Note that your DNS name server must support round robin names.
So that ClusterCATS operates effectively with round robin DNS, you need to make sure it is configured properly. For example, for a single location Web server farm consisting of four servers, you need to configure round robin DNS across all four servers for the domain name and individual IP addresses for each server name. As an example, your DNS tables would look something like the table below.
Example DNS Tables with Round Robin Enabled
|
Host Name
| IP Address
|
www.mycompany.com
| 193.168.0.1
|
193.168.0.2
|
193.168.0.3
|
193.168.0.4
|
www1.mycompany.com
| 193.168.0.1
|
www2.mycompany.com
| 193.168.0.2
|
www3.mycompany.com
| 193.168.0.3
|
www4.mycompany.com
| 193.168.0.4
|
round robin DNS distributes the initial domain level requests across all four servers. From there, ClusterCATS distributes load to avoid failed or overloaded servers.
|