User can set multiple KDC, not only master but also slave, for achieving redundancy.

Release:
Component: UIMXAP

User can add multiple "KDC" parameters within [realms] section on krb5.conf that xenapp probe refers.

Here is an example of krb5.conf that multiple KDCs are set on.

[libdefaults]
    default_realm = ATHENA.MIT.EDU
    dns_lookup_kdc = true
    dns_lookup_realm = false

[realms]
    ATHENA.MIT.EDU = {
        kdc = kerberos.mit.edu
        kdc = kerberos-1.mit.edu
        kdc = kerberos-2.mit.edu
        admin_server = kerberos.mit.edu
        master_kdc = kerberos.mit.edu
    }
    EXAMPLE.COM = {
        kdc = kerberos.example.com
        kdc = kerberos-1.example.com
        admin_server = kerberos.example.com
    }

[domain_realm]
    mit.edu = ATHENA.MIT.EDU

[capaths]
    ATHENA.MIT.EDU = {
           EXAMPLE.COM = .
    }
    EXAMPLE.COM = {
           ATHENA.MIT.EDU = .
    }

See the detail below link.
MIT Kerberos Documentation > krb5.conf