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A Name Authority Pointer (NAPTR) is a type of resource record in the Domain Name System of the Internet. NAPTR records are most commonly used for applications in Internet telephony, for example, in the mapping of servers and user addresses in the Session Initiation Protocol (SIP). The combination of NAPTR records with Service Records (SRV) allows the chaining of multiple records to form complex rewrite rules which produce new domain labels or uniform resource identifiers (URIs). The DNS type code for the NAPTR record is 35. == Rationale == Uniform Resource Names (URNs) are a subset of Uniform Resource Identifiers (URIs) used for abstract identifiers, such as a person's name or their telephone number. For URNs to be meaningful, they must be mapped to a concrete resource of some sort. Uniform Resource Locators (URLs) are often used to describe such resources, such as a computer hostname, or a local file. The NAPTR record aids in the standardization of URNs. NAPTR records map between sets of URNs, URLs and plain domain names and suggest to clients the protocols available for communication with the mapped resource. Each NAPTR record contains a service name, a set of flags, a regular expression rule, an order value, a preference and a replacement pattern. Multiple records can be chained together in a cascade to rewrite URIs in deterministic ways. These cascading rules have been standardized in RFC2915 and RFC3403. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「NAPTR record」の詳細全文を読む スポンサード リンク
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