You can modify your /etc/nsswitch.conf file to customize where each service gets its information. The default settings are stored in /etc/nsswitch.ldap and ldapclient uses this file to create your /etc/nsswitch.conf file when the client is initialized.
If you want to enable DNS by setting up a /etc/resolv.conf file, you will want to add DNS to your hosts lines as shown below.
hosts: ldap dns [NOTFOUND=return] files
You can change any of the services, but be careful, because if the data is not populated on the server for the service specified things will stop working. In some cases files may not be setup by default as well.