Enable SOA serial autoincrement
    
    SOA serial autoincrement is a requirement for major DNS features,
    e.g. zone transfers or DNSSEC. Enable it by default in named.conf
    both for new and upgraded installations. Name of the bind-dyndb-ldap
    option is "serial_autoincrement".
    
    From now on, idnsSOAserial attribute also has to be put to
    replication agreement exclude list as serial will be incremented
    on each DNS server separately and won't be shared. Exclude list
    has to be updated both for new replication agreements and the
    current ones.
    
    Minimum number of connections for bind-dyndb-ldap has been rised
    to 4 connections, the setting will be updated during package upgrade.
    
    https://fedorahosted.org/freeipa/ticket/2554