Icinga HA - checks does not work when one master is down

I have single master with a set of clients. For security reasons, direction of connection is always client to server [ server does not connect to client ]. Also all checks runs on clients ( command_endpoint ).

I wanted to add HA for monitoring. I added a second node to master zone & updated zones.conf etc etc. All was okay, except few clients which were behind firewall. firewall was not open to the second master for these clients. all these clients were reported as down and checks were not getting executed ( due to dependency ). While searching the forums i came across a post that states both master must be always available. Is icinga HA is actually only a cluster to distribute load ? Does it not provide High availability function ? ( monitoring works with only one master when other is down )

Hello Manoj,
Welcome to the Icinga community. I hope your are doing well. When high availability is configured correctly you are able to take one Master offline and the other Master will continue with checks and sending out notification as scheduled.
When you added your 2nd master did you update the zones.conf file on your agents with the new master details? Please review the HA master setup with agents webpage for more details.