High-level lookups:

the dns library provides several easy-to-use dns lookup routines: dns_ip4, dns_ip4_qualify, dns_name4, dns_mx, and dns_txt.

dns_ip4_qualify supports the traditional configuration mechanisms for hostname rewriting: $localdomain, /etc/resolv.conf, and gethostname. it also supports a powerful new user-controlled rewriting mechanism.

the functions that read /etc/resolv.conf automatically reread it every ten minutes, so system administrators don't have to kill long-running programs.

low-level lookups:

the dns_domain_* and dns_packet_* functions make it easy to safely parse dns packets. the dns_transmit_* functions send dns queries of arbitrary types to arbitrary servers. these are the functions used in the dnscache program.

see http://cr.yp.to/djbdns/blurb/library.html for details.

this package contains the header files and the static library.