When trying to setup HA, I received the error "An error occurred during configuration of the HA Agent on the host." Looking deeper under "Tasks & Events" I was able to see the error was that the "configuration of the host IP address is inconsistent on host ESX1.local.com: address resolved to 192.168.x.x and 172.168.x.x"
I looked in
/etc/FT_HOSTS (didn't exist for me)
checked all my DNS entries, even made sure they were case sensative (someone elses blog said that mattered)
I did a hostname -i and a hostname -s, all returned good results.
I also read that your /etc/hosts file must be
IPaddress (x.x.x.x) then Hostname, then FQDN, in that order, and contain all ESX hosts, I tried that, it didn't help.
I did a /opt/vmware/aam/bin ./ft_gethostbyname, it gave me an incorrect result, for a service console that no longer existed.
Then after hours of pulling my hair out
I then looked in the /etc/opt/vmware/aam/FT_HOSTS , it had old bad information.
I deleted that file, then disabled HA on the cluster, then re-enabled it and FINALLY HA installed properly.