System Administration Guide: Naming and Directory Services (DNS, NIS, and LDAP)

LDAP Naming Service Versus Other Naming Services

Below is a quick comparison between FNS, DNS, NIS, NIS+ and LDAP naming services.

	DNS	NIS	NIS+	FNS	LDAP
NAMESPACE	Hierarchical	Flat	Hierarchical	Hierarchical	Hierarchical
DATA STORAGE	Files/ resource records	2 column maps	Multi columned tables	Maps	Directories [varied] Indexed database
SERVERS	Master/slave	Master /slave	Root master/ non-root master; primary/ secondary; cache/stub	N/A	Master/replica Multi master replica
SECURITY	none	None (root or nothing)	DES Authentication	None (root or nothing)	SSL, varied
TRANSPORT	TCP/IP	RPC	RPC	RPC	TCP/IP
SCALE	Global	LAN	LAN	Global (with DNS)/LAN	Global

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.

Advantages of LDAP Naming Service

LDAP gives you the ability to consolidate information by replacing application-specific databases; reduces the number of distinct databases to be managed
LDAP allows for more frequent data synchronization between masters and replicas
LDAP is multi-platform and multi-vendor compatible

Disadvantages of LDAP Naming Service

The following are some disadvantages to using LDAP instead of other naming services.

There is no support for pre-Solaris 8 clients
An LDAP server cannot be its own client
Setting up and managing an LDAP naming service is more complex and requires careful planning

Note –

A directory server (an LDAP server) cannot be its own client. In other words, you cannot configure the machine that is running the directory server software to become an LDAP naming service client.