DNS is a standard, enterprise-grade, highly-scalable and reliable mechanism for mapping between hostnames and IP addresses. Use of working DNS servers is a best practice and will generally yield the best results. In some environments, there may be a subset of hosts that can be resolved only in NIS or LDAP maps. If this is the case in your environment, enable non-DNS host resolution and configure the appropriate directory service(s). If LDAP is used for host resolution, the hosts map must be located at the standard DN in your database: ou=Hosts,(Base DN), and must use the standard schema. When this mode is used with NFS sharing by netgroups, it may be necessary for client systems to use the same hostname resolution mechanism configured on the appliance, or NFS sharing exceptions may not work correctly.
When non- DNS host resolution is enabled, DNS will still be used. Only if an address or hostname cannot be resolved using DNS will NIS (if enabled) and then LDAP (if enabled) be used to resolve the name or address. This can have confusing and seemingly inconsistent results. You can validate host resolution results using the getent CLI command described above.
Use of these options is strongly discouraged.