You don’t need to do much to your network to make contacts service available to users. You don’t even have to alter the directory. One requirement, though, is that the Mac on which you run Contacts Server must be configured as an Open Directory master. To do so, you use the Open Directory pane of the Server app, as described in Chapter 5. This configuration is necessary because Mac client users are provisioned in Open Directory; in other words, the directory services provide authentication and access privileges.
A DNS entry can be helpful in mid-to-large-sized networks but is unnecessary for home networks. And as with all services, you may need port forwarding if users access the service from the Internet.
Although it’s not a requirement, you can add a service record (SRV record) for CardDAV to a DNS server to help clients connect to the contacts service, particularly across the Internet. The service record can be on the DNS service running in OS X Server or on another server. The port number used depends on whether you’re using a Secure Sockets Layer (SSL) certificate for contacts service.
If you’re using an SSL certificate, the SRV record should map
carddavs._tcp for port 8443 of the server’s host name:
_carddavs._tcp 86400 IN SRV 0 1 8443
If you’re not using SSL for contacts service, add a record that maps
_card dav._tcp for port 8008 to the server host name. For example:
_carddavs._tcp 86400 IN SRV 0 1 8008