Specifies the type of address for performing a
lookup operation for a symbolic host name or for a host
address from a remote host.
Specification of dns(16) as the value for this object
means that a function such as, for example, getaddrinfo()
or gethostbyname() should be performed to return one or
more numeric addresses. Use of a value of either ipv4(1)
or ipv6(2) means that a functions such as, for example,
getnameinfo() or gethostbyaddr() should be used to return
the symbolic names associated with a host.