Prequisites and understanding of HA installation

For HA, you need to use the FQDN instead of the IP address, and should be resolvable.  Instead of making manual entries in the /etc/hosts file, you can use the DNS server to resolve them.

1. DNS entries:- 

Let's suppose:
Master - 192.0.0.1/node1.example.com
Slave - 192.0.0.2/node2.example.com
Cluster address - cluster.example.com

When you install FAS you set the cluster address as something like cluster.example.com which resolves to both 192.168.0.1 & 192.168.0.2. Then requests to cluster.example.com can be routed to either node, each node will have an LB element and be able to route requests to the AS element on either node.
On the DNS server, entries should be like the following:-

node1.example.com - 192.0.0.1
node2.example.com - 192.0.0.2

cluster.example..com  - 192.0.0.1
cluster.example.com  - 192.0.0.2

Cluster address doesn't have its own IP, it will be resolved by both the master and slave IP's. Please make correct entries it's very important in a cluster environment.

2. Cluster Installation steps:-

On Master Node:- 

FAS Installation 

accept.eula=yes

JDKPath=/usr/java/latest

topology.type=multibox

node.type=master

bind.address.service=master_FQDN

bind.address.management=master_FQDN

cluster.address=cluster_address

FCSDK Installation- 

You need to install FCSDK on the master node only by performing the below steps:

accept.eula=yes

JDKPath=/usr/java/latest

packs=COMMON,GATEWAY,CORE_SDK,SAMPLE_APP (Removing media broker because you will install it on saparate server)

appserver.admin.address=master_FQDN

gateway.controlled_domain=cluster_address

On Slave Node:- 

Only the FAS will be installed on the slave only by performing the below steps:

FAS Installation 

accept.eula=yes

JDKPath=/usr/java/latest

topology.type=multibox

node.type=slave

bind.address.service=slave_FQDN

bind.address.management=slave_FQDN

cluster.address=cluster_address

##Slave Node Configuration

master.address=master_FQDN

master.port=9999

MB Node's:-

Please refer article: https://cba-support.zendesk.com/hc/en-us/articles/360001010277-Install-and-Configure-Media-Broker for this.