What does an LDAP directory entry consist of?

An entry (Eintrag) is a set of attributes, each made of an attribute type and one or more values; the entry is named by its DN, and its objectClass values define which attributes it must and may contain.

* One entry: the DN names it, the object classes set its rules, the attributes carry the data. *

Reading an entry top-down:

1. Distinguished Name: dn: uid=juser,ou=People,ou=webdesign,c=de,o=acme, the unique name and position in the tree.
2. Schema definition: several objectClass values (top, person, organizationalPerson, inetOrgPerson). They state which attributes this entry is allowed or required to have.
3. User data (Nutzdaten): the actual attribute type/value pairs such as cn: Joe User, sn: User, mail: joe.user@acme.de, telephoneNumber: +49 123 12345.

Each attribute type has a syntax defined in the schema (a telephone number, a directory string, a binary certificate), and every value must follow it. An attribute type is defined as single-valued or multi-valued: cn is multi-valued, so the same entry can carry both cn: Joe User and cn: User Joe, while c is single-valued.

Go deeper:

• RFC 4512, Section 2.2: Structure of an Entry — the formal definition of entries, attributes and values.