res_hnok(3C)

NAME
     res_hnok, res_ownok, res_mailok, res_dnok - name service record validity
     routines

SYNOPSIS
     #include <resolv.h>

     int res_hnok(char *dn);

     int res_ownok(char *dn);

     int res_mailok(char *dn);

     int res_dnok(char *dn);

DESCRIPTION
     Helper functions that determine the validity of a few types of name-
     service related records.  Functions return 1 for valid, 0 for invalid.

     res_hnok determines if the given argument is a valid hostname.  res_ownok
     is similar, but allows for "*" in the first label.  For example:
     *.sgi.com.  This is appropriate for A or MX record owners.  res_mailok
     allows for any printable characters in the first label.  The rest of the
     name must look like a valid hostname.  Useful for SOA RNAMEs and RP
     RNAMEs.  Finally, res_dnok follows RFC 1034 for valid domain name
     characters.

FILES
     /etc/resolv.conf

SEE ALSO
     resolver(4), named(1M).