-- hostname
-- IP address
-- Cluster Status
-- inconsistency

When we navigate to Admin GUI->Operations->Cluster Status we see our primary server listed with its hostname (FQDN) while the secondary listed by its IP address only (or the other way around).

Make sure you have both primary and secondary nodes isted by their hostnames and IP addresses accordingly within:

/etc/hosts file

and also:

<fdhome>/lib/admin/config/servers file

Examples:
===
/etc/hosts (order and format my differ in different OS)
...
10.232.10.41   primary.domain.com         primary
10.232.10.42   secondary.domain.com    secondary
...
===
<fdhome>/lib/admin/config/servers
#
# @(#) $Id: servers,v 1.2 2004/08/20 02:17:25 eijih Exp $
#
# Do not delete the SecureTransport VERSION line below.
# ~VERSION~ 1
#
# We can't use ':' to separate the fields in this file because of the
# HTTP scheme, which by necessity contains a ':'. Use tabs instead.
#
# Server Name (text label)      Server URL
#
# host.somedomain.com   https://host.somedomain.com:444
10.232.10.41   https://primary.domain.com:444
10.232.10.42   https://secondary.domain.com:444

The above information applies only to UNIX OS