ISC's libbind provides the standard resolver library, along with header files and documentation, for communicating with domain name servers, retrieving network host entries from /etc/hosts or via DNS, converting CIDR network addresses, perform Hesiod information lookups, retrieve network entries from /etc/networks, implement TSIG transaction/request security of DNS messages, perform name-to-address and address-to-name translations, utilize /etc/resolv.conf for resolver configuration. It contains many of the same historical functions and headers included with many Unix operating systems. Originally written for BIND 8, it was included in BIND 9 as optionally-compiled code through release 9.5. It has been removed from subsequent releases of BIND 9 and is now provided as a separate package.