IBM Curam V6, Business Analysis and Design Set 10

Your company contains an active directory domain name contoso.com. The network contains three subnets that they are separated by firewall. The domain has a server named server5 that has active directory lightweight services. Server5 only support encrypted LDAP connection. You need to configure to ensure the client computers can access the LDAP services on server5. Which port should you allow through windows firewall.