DNS error messages such as missing reverse DNS zone are not propagated to UI although the information can found at foreman log:

Processing HostsController#create (for 10.35.3.235 at 2011-03-23 15:56:28) [POST]
Parameters: {"commit"=>"Submit", "action"=>"create", "authenticity_token"=>"lDw7lOvmFCZHAYU7kllO19x9ypCHKWBoTgD6jT6RHZM=", "controller"=>"hosts", "host"=>{"comment"=>"", "serial"=>"", "architecture_id"=>"1", "subnet_id"=>"2", "managed"=>"true", "name"=>"test5", "host_parameters_attributes"=>{"0"=>{"name"=>"", "nested"=>"", "value"=>"", "_destroy"=>""}}, "puppetmaster_name"=>"puppet", "mac"=>"00:1a:4a:16:97:a0", "domain_id"=>"1", "enabled"=>"1", "root_pass"=>"[FILTERED]", "medium_id"=>"1", "build"=>"1", "hostgroup_id"=>"1", "is_owned_by"=>"1-Users", "ptable_id"=>"1", "ip"=>"10.35.97.160", "environment_id"=>"1", "model_id"=>"", "disk"=>"", "puppetclass_ids"=>[""], "operatingsystem_id"=>"1"}}
Add the DNS record for test5.qa.lab.tlv.redhat.com/10.35.97.160
Add the Reverse DNS records for test5.qa.lab.tlv.redhat.com/160.97.35.10.in-addr.arpa
Failed to create the Reverse DNS record: DNS create failed for test5.qa.lab.tlv.redhat.com
Delete the DNS records for test5.qa.lab.tlv.redhat.com/10.35.97.160
Rendering template within layouts/application
Rendering hosts/new
Completed in 470ms (View: 204, DB: 14) | 200 OK [http://10.35.64.2/hosts]