LDAP is the lightweight directory access protocol, which is based on a client-server model. In this model, a client makes a TCP connection to an LDAP server, over which it sends requests and receives responses. The LDAP information model is based on the entry, which contains information about some object (for example, a person). Entries are composed of attributes, which have a type and one or more values. Each attribute has a syntax that determines what kinds of values are allowed in the attribute (for example, ASCII characters or a jpeg photograph) and how those values behave during directory operations (for example, whether case is significant during comparisons). Entries may be organized in a tree structure, usually based on political, geographical, or organizational boundaries. Each entry is uniquely named relative to its sibling entries by its relative distinguished name (RDN) consisting of one or more distinguished attribute values from the entry. At most, one value from each attribute may be used in the RDN. For example, the entry for the person Babs Jensen might be named with the Barbara Jensen value from the commonName attribute. A globally unique name for an entry, called a distinguished name or DN, is constructed by concatenating the sequence of RDNs from the entry up to the root of the tree. For example, if Babs worked for the University of Michigan, the DN of her U-M entry might be the following: cn=Barbara Jensen, o=University of Michigan, c=US Operations are provided to authenticate, search for and retrieve information, modify information, and add and delete entries from the tree.