Following are the logs captured..
Oct 5 15:41:08 SVR-ACS adclient[18425]: INFO base.bind.ad
ConnectToServer: fetch("") from aa-dc01.com:389 failed
(Reason: fetch : Can't contact LDAP server)
Oct 5 15:41:18 SVR-ACS adclient[18425]: INFO base.bind.ad
ConnectToServer: fetch("") from aa-dc02.com:389 failed
(Reason: fetch : Can't contact LDAP server)
Oct 5 15:41:23 SVR-ACS adclient[18425]: INFO base.bind.ad
ConnectToServer: fetch("") from aa-dca01.com:389 failed
(Reason: fetch : Can't contact LDAP server)
Oct 5 15:43:18 SVR-ACS adclient[18425]: INFO base.bind.ad
ConnectToServer: fetch("") from aa-dc04.com:389 failed
(Reason: fetch : Can't contact LDAP server)