Host is a very powerful DNS query and testing command-line tool. Major differences with the ancient version of the program with the same name that's included in the BIND-4 and BIND-8 distributions: - Major overhaul of the entire code including rigid error checking, and verbose error messages. Several sections have been rewritten from scratch. Documentation has been added. Syntax extended. - It is now possible to do recursive listings into delegated zones. - Maintain resource record statistics and host count during zone listings. - Check for various extraneous conditions during zone listings. - Check for illegal domain names containing invalid characters. - Verify that certain domain names represent canonical host names. - Perform ttl consistency checking during zone listings. - Exploit multiple server addresses if available. - Option to exploit only primary server for zone transfers. - Option to exclude info from names that do not reside in a zone. - Implement timeout handling during connect and read. - Write resource record output to optional log file. - Special MB tracing by recursively expanding MR and MG records. - Special mode to check SOA records at each nameserver for a zone. - Special mode to check reverse mappings of host addresses. - Configurable default options in HOST_DEFAULTS environment variable. - Implement new resource record types from RFCs 1183, 1348, 1664, 1712, 1876 and 1886. Basic experimental NSAP support as defined in RFC 1637.