res_query() — Resolver query for domain name servers

Standards

Format

#define _XOPEN_SOURCE_EXTENDED 1
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <resolv.h>

int res_query(const char *dname, int class, int type, u_char *answer, int anslen);

General description

This routine is one of several functions used for making, sending and interpreting query and reply messages with Internet domain name servers (DNS).

The res_query() function provides an interface to the server query mechanism. It constructs a query, sends it to the local server, awaits a response, and makes preliminary checks on the reply. The query requests information of the specified type and class for the specified fully-qualified domain name dname. The reply message is left in the answer buffer with length anslen supplied by the caller.

Returned value

If successful, res_query() returns the reply message in the answer buffer with length anslen.

Related information

• arpa/nameser.h
• netinet/in.h
• resolv.h
• sys/types.h
• dn_comp() — Resolver domain name compression
• dn_expand() — Resolver domain name expansion
• dn_find() — Resolver domain name find
• dn_skipname() — Resolver domain name skipping
• res_init() — Domain name resolver initialization
• res_mkquery() — Make resolver query for domain name servers
• res_querydomain() — Build domain name and resolver query
• res_search() — Resolver query for domain name servers
• res_send() — Send resolver query for domain name servers