RFC1034 (November 1987, Domain Names - Concepts and Facilities) discusses the architecture of the DNS, and RFC1035 (November 1987, Domain Names— Implementation and Specification) spells out the implementation details.
Recognizing that the DNS is the only truly global Internet directory but that it could never support per-resource URL resolution, RFC2168 (June 1996, Resolution of Uniform Resource Identifiers, Using the Domain Name System) proposes a hybrid approach: a DNS resource record called Naming Authority Pointer (NAPTR) that maps parts of URIs to domain names. The idea is that a URN can refer, through DNS, to a resolver that produces an address.
LDAP’s purpose was to lower the “high cost-of-entry” that had prevented the widespread use of X.500-style directory services on the Internet. The core protocol is defined in a series that begins with RFC1487 (July 1993, X.500 Lightweight Directory Access Protocol) and ends with RFC2251 (December 1997, Lightweight Directory Access Protocol (v3)). RFC2252 (December 1997, Lightweight Directory Access Protocol (v3): Attribute Syntax Definitions) defines “the framework for developing schemas for directories accessible via the Lightweight Directory Access Protocol.” RFC2254 (December 1997, The String Representation of LDAP Search Filters) defines the LDAP query language illustrated in Chapter 14.
Despite LDAP’s success, the vision of a consolidated Internet white pages service remains elusive. There are many public LDAP directories, ...