As mentioned in Chapter 1, Cluster Basics and Installation on CentOS 7, since a cluster is by definition a group of computers (which we have been referring to as nodes or members) that work together so that the set is seen as a single system from the outside, we need to ensure that end users and clients see it that way.
For this reason, the last thing that we will do in this chapter is configure a virtual IP, which is the address that external clients will use to connect to our cluster. Note that in an ordinary, non-cluster environment, you can use tools, such as ifconfig to configure a virtual IP for your system.
However, in our case, we will use nothing more and nothing less than PCS and perform two operations at once:
Creating the IPv4 address
Assigning it to the cluster as a whole