X.500 is the set of ITU-T computer networking standards covering electronic directory services such as white pages, Knowbot and whois. X.500 was jointly developed with ISO as part of the Open Systems Interconnect suite of protocols, in order to support the requirements of X.400 electronic mail and name lookup. The ITU Telecommunication Standardization Sector (ITU-T) coordinates standards for telecommunications on behalf of the International Telecommunication Union (ITU) and is based in Geneva, Switzerland. ... A computer network is a system for communication among two or more computers. ... The word standard has several meanings: Originally, standard referred to a conspicuous object used as a rallying point in battle. ... A directory service organizes computerized content and runs on a directory server computer. ... A white pages is a telephone directory listing of subscriber names, addresses, and telephone numbers. ... A knowbot is a kind of bot that collects information by automatically gathering certain specified information from web sites. ... WHOIS is a TCP-based query/response protocol which is widely used for querying a database in order to determine the owner of a domain name, an IP address, or an autonomous system number, on the Internet. ... Logo of the International Organization for Standardization The International Organization for Standardization (ISO or iso) is an international standard-setting body composed of representatives from national standards bodies. ... Starting in 1982, the International Organization for Standardization (ISO) along with the ITU-T initiated a new effort in networking called Open Systems Interconnect or OSI. Prior to OSI, networking was completely vendor-developed and proprietary, with standards such as SNA, Decnet, and XNS. OSI was a new industry effort... In computing, X.400 is a OSI standard developed by the ITU-T (at the time the CCITT) and promulgated by ISO for the exchange of email (at the time called IPMs - Inter Personal Messages). ...

The protocols defined by X.500 included Directory Access Protocol, Directory System Protocol, Directory Information Shadowing Protocol, and Directory Operational Bindings Management Protocol. DAP is a computer networking standard promulgated by ITU-T and ISO in 1988 for accessing an X.500 directory service. ...

One of the X.500 series of specifications which has seen the widest use is not one of the directory protocols, however, but X.509, the specification of public-key certificates. In cryptography, X.509 is an ITU-T standard for public key infrastructure (PKI). ...

Compare: LDAP. In computer networking, the Lightweight Directory Access Protocol, or LDAP, is a standardized networking protocol designed for querying and modifying directory services. ...

External links

• Understanding X.500 - The Directory (Copyright 1994, 1996 D W Chadwick.)

Article based on X.500 at FOLDOC, used with permission. Received: from diver. ...