Using Fully Qualified Domain Names

One significant difference between an LDAP client and a NIS or NIS+ client is that an LDAP client always returns a Fully Qualified Domain Name (FQDN) for a host name, similar to those returned by DNS. For example, if your domain name is

west.example.net

both gethostbyname() and getipnodebyname() return the FQDN version when looking up the hostname server.

server.west.example.net

Also if you use interface specific aliases like server-#, a long list of fully qualified host names is returned. If you are using host names to share file systems or have other such checks you need to account for it. This is especially true if you assume non-FQDN for local hosts and FQDN only for remote DNS resolved hosts. If you setup LDAP with a different domain name from DNS you might be surprised when the same host has two different FQDNs, depending on the lookup source.