Specifies the domain prefix used for Hesiod queries. In almost all cases, you should specify "lhs=.ns". The default value if you do not specify an lhs value is no domain prefix, which is not compatible with most Hesiod domains.
Specifies the default Hesiod domain; this value may be overridden by the HES_DOMAIN environment variable. You must specify an rhs line for the Hesiod library to work properly.
Specifies which DNS classes Hesiod should do lookups in. Possible values are IN (the preferred class) and HS (the deprecated class, still used by some sites). You may specify both classes separated by a comma to try one class first and then the other if no entry is available in the first class. The default value of the classes variable is "IN,HS".