Bug originally reported by Michal Bruncko: https://bugzilla.redhat.com/show_bug.cgi?id=520509

Description of problem:

After restarting LDAP server, dyndb-ldap module cannot connect (or reconnect) to LDAP server. I think that ldap module guess, that connection is still alive, but it isn't.

from named.log:

named[5306]: bind to LDAP server failed: Can't contact LDAP server

...message are inserted repeatedly after every incoming DNS query and all DNS responses had SERFAIL status.

If I also restart named daemon after restarting LDAP server, all is OK and ldap module successfully creates new connection.

Steps to Reproduce:
0. precondition: running ldap server
1. start named daemon with configured ldap storage for dns zones
1. restart ldap server
1. try to query some dns record that is stored in ldap directory, the result is always SERVFAIL

Additional info:

If I try to query the same hostname after step 4, that I queried after step 2, I got the correct DNS response from named, because I think, ldap module uses cache for latest queried dns records. But all other non-cached records will never be translated.