System Administration Guide: Naming and Directory Services (NIS+)

NIS+ Naming Conventions

Objects in an NIS+ namespace can be identified with two types of names: partially-qualified and fully qualified. A partially qualified name, also called a simple name, is simply the name of the object or any portion of the fully qualified name. If during any administration operation you type the partially qualified name of an object or principal, NIS+ will attempt to expand the name into its fully qualified version. For details, see NIS+ Naming Conventions.

A fully qualified name is the complete name of the object, including all the information necessary to locate it in the namespace, such as its parent directory, if it has one, and its complete domain name, including a trailing dot.

This varies among different types of objects, so the conventions for each type, as well as for NIS+ principals, is described separately. This namespace will be used as an example:

Diagram shows example namespace

The fully qualified names for all the objects in this namespace, including NIS+ principals, are summarized below.

Figure 2–4 Fully-Qualified Names of NIS+ Namespace Components

Diagram shows FQDNs for the namespace

NIS+ Domain Names

A fully qualified NIS+ domain name is formed from left to right, starting with the local domain and ending with the root domain: (root domain) (subdomain) (a third level subdomain)

The first line above shows the name of the root domain. The root domain must always have at least two elements (labels) and must end in a dot. The last (right most) label may be anything you want, but in order to maintain Internet compatibility, the last element must be either an Internet organizational name (as shown below), or a two or three character geographic identifier such as .jp for Japan.

Table 2–4 Internet Organizational Domains




Commercial organizations 


Educational institutions 


Government institutions 


Military groups 


Major network support centers 


Nonprofit organizations and others 


International organizations 

The second and third lines above show the names of lower-level domains.

NIS+ Directory Object Names

A directory's simple name is simply the name of the directory object. Its fully qualified name consists of its simple name plus the fully qualified name of its domain (which always includes a trailing dot):

groups_dir (simple name) (fully qualified name)

If you set up an unusual hierarchy in which several layers of directories do not form a domain, be sure to include the names of the intermediate directories. For example:

The simple name is normally used from within the same domain, and the fully qualified name is normally used from a remote domain. However, by specifying search paths in a domain's NIS_PATH environment variable, you can use the simple name from remote domains (see NIS+ NIS_PATH Environment Variable).

NIS+ Tables and Group Names

Fully qualified table and group names are formed by starting with the object name and appending the directory name, followed by the fully qualified domain name. Remember that all system table objects are stored in an org_dir directory and all group objects are stored in a groups_dir directory. (If you create your own NIS+ tables, you can store them anywhere you like.) Here are some examples of group and table names:

NIS+ Table Entry Names

To identify an entry in an NIS+ table, you need to identify the table object and the entry within it. This type of name is called an indexed name. It has the following syntax:


Column is the name of the table column. Value is the actual value of that column. Tablename is the fully qualified name of the table object. Here are a few examples of entries in the hosts table:


You can use as few column-value pairs inside the brackets as required to uniquely identify the table entry.

Some NIS+ administrative commands accept variations on this syntax. For details, see the nistbladm, nismatch, and nisgrep commands in Part 2.

NIS+ Host Names

Host names may contain up to 24 characters. Letters, numbers, the dash (-) and underscore (_) characters are allowed in host names. Host names are not case sensitive (that is, upper and lower case letters are treated as the same). The first character of a host name must be a letter of the alphabet. Blank spaces are not permitted in host names.

Note –

Dots (.) are not permitted in host names. For example, a host name such as doc.2 is not permitted. Dots are not allowed in host names even if they are enclosed in quotes. For example, `doc.2' is not permitted. Dots are only used as part of a fully qualified host name to identify the domain components. For example, is a correct fully qualified host name.

Domains and hosts should not have the same name. For example, if you have a sales domain you should not have a machine named sales. Similarly, if you have a machine named home, you do not want to create a domain named home. This caution also applies to subdomains. For example, if you have a machine named west you don't want to create a subdomain.

NIS+ Principal Names

NIS+ principal names are sometimes confused with Secure RPC netnames. However, one difference is worth pointing out now because it can cause confusion: NIS+ principal names always end in a dot and Secure RPC netnames never do. The following list provides examples.

NIS+ principal name

Secure RPC netname

Also, even though credentials for principals are stored in a cred table, neither the name of the cred table nor the name of the org_dir directory is included in the principal name.

Accepted Name Symbols in NIS+

You can form namespace names from any printable character in the ISO Latin 1 set. However, the names cannot start with these characters: @ < > + [ ] - / = . , : ;

To use a string, enclose it in double quotes. To use a quote sign in the name, quote the sign too (for example, to use o'henry, type o”'”henry). To include white space (as in John Smith), use double quotes within single quotes, like this:

`”John Smith”`

See NIS+ Host Names for restrictions that apply to host names.

NIS+ Name Expansion

Entering fully qualified names with your NIS+ commands can quickly become tedious. To ease the task, NIS+ provides a name-expansion facility. When you enter a partially qualified name, NIS+ attempts to find the object by looking for it under different directories. It starts by looking in the default domain. This is the home domain of the client from which you type the command. If it does not find the object in the default domain, NIS+ searches through each of the default domain's parent directories in ascending order until it finds the object. It stops after reaching a name with only two labels. Here are some examples (assume you are logged onto a client that belongs to the domain).

Diagram shows examples of name extentions