Toad for Oracle is not displaying the database names in the drop-down list when the first LDAP server is down and a secondary LDAP server exists in the LDAP.ORA file.
When the first ldap server in the ldap.ora file is down or offline, Toad does not display the db names list that is supposed to be coming from the second ldap server in the ldap.ora file.
For testing purposes, user switched the two ldap servers around by moving the second server as the first one in the ldap.ora file (see example below). Toad started working as normal again; Toad was able to display the db names list and it was able to connect as well.
Switch the ldap servers around in the LDAP.ORA file as noted above.
If the db names list does not show due to the 1st ldap server being down, manually type in the database name and Toad will be able to connect. However it will take about a minute to connect (the first workaround above does not encounter this connection delay).
Waiting for fix in a future release of Toad for Oracle.