As far as I understand from the code, libldap already behaves like that, i.e. it loops through all the hosts returned by getaddrinfo(3). What's missing (in your configuration of ldapsearch) is a network timeout parameter. Right now, you can set it either using NETWORK_TIMEOUT in ldap.conf(5) or passing the command-line switch -o nettimeout=<timeout>. I understand the latter is not documented in ldapsearch(1), although it appears in the usage message of all tools.

As I'd consider this issue a software usage question rather than a bug (except for the missing documentation), I encourage you to continue discussion on the openldap-technical mailing list.

p.