Implements a resolver for DNS queries.
TIdDNSResolver = class(TIdTCPConnection);
TIdDNSResolver is a TIdTCPClient descendant that provides an implementation of a resolver for DNS (Domain Name Server) queries using the DNS protocol. The DNS protocol is described in the Internet Standards documents:
TIdDNSResolver provides facilities for accessing the Domain Name Space and Resource Records retrieved from a DNS Server using queries for specified domain names, resource types, and resource classes.
TIdDNSResolver provides properties and methods that simplify the process of creating a valid DNS query, and accessing the resource records returned in the query results.
Set AllowRecursiveQueries to the value to be used in the DNS Query header. AllowRecursiveQueries permits a DNS server to pursue the query for DNS resource records on another name server. AllowRecursiveQueries has no effect if the DNS server does not implement recursive queries.
Use the Resolve method to peform a DNS Query for the specified domain name. Resolve creates the DNS Query packet, including the DNS header, transmits the request to the DNS host, and captures and parses the query results.
Use QueryResult to determine the number of resource records returned by the QueryClass, QueryType, and DomainName in the DNS Query, and to access the TResultRecord object instances containing the data for the resource records. Items in QueryResults may also be cast to an instance of a TResultRecord descendant class to access additional properties and methods based on its resource record type and class.
Currently, the TIdDNSResolver implementation does not support all aspects of the DNS protocol, and includes the following limitations:
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