When building your 4.3BSD system you may either build the C library to use the name server resolver routines or use the host table lookup routines to do host name and address resolution. The default resolver for 4.3BSD uses the name server. Newer BSD systems include both name server and host table functionality with preference given to the name server if there is one or if there is a /etc/resolv.conf file.
Building the C library to use the name server changes the way gethostbyname(3N), gethostbyaddr(3N), and sethostent(3N) do their functions. The name server renders gethostent(3N) obsolete, since it has no concept of a next line in the database. These library calls are built with the resolver routines needed to query the name server.
The resolver contains functions that build query packets and exchange them with name servers.
Before building the 4.3BSD C library, set the variable HOSTLOOKUP equal to named in /usr/src/lib/libc/Makefile. You then make and install the C library and compiler and then compile the rest of the 4.3BSD system. For more information see section 6.6 of ``Installing and Operating 4.3BSD on the VAX''.
If your operating system isn't VAX 4.3BSD, it is probably the case that your vendor has included resolver support in the supplied C Library. You should consult your vendor's documentation to find out what has to be done to enable resolver support. Note that your vendor's resolver may be out of date with respect to the one shipped with BIND, and that you might want to build BIND's resolver library and install it, and its include files, into your system's compile/link path so that your own network applications will be able to use the newer features.