@type t() :: %{
  optional(:ip) => :inet.ip_address(),
  optional(:mask) => non_neg_integer(),
  optional(:siaddr) => :inet.ip_address(),
  optional(:subnet) => :inet.ip_address(),
  optional(:timezone) => String.t(),
  optional(:router) => [:inet.ip_address()],
  optional(:dns) => [:inet.ip_address()],
  optional(:lprsrv) => [:inet.ip_address()],
  optional(:hostname) => String.t(),
  optional(:bootsize) => String.t(),
  optional(:domain) => String.t(),
  optional(:swapsrv) => :inet.ip_address(),
  optional(:rootpath) => String.t(),
  optional(:ipttl) => non_neg_integer(),
  optional(:mtu) => non_neg_integer(),
  optional(:broadcast) => :inet.ip_address(),
  optional(:routes) => [:inet.ip_address()],
  optional(:nisdomain) => String.t(),
  optional(:nissrv) => [:inet.ip_address()],
  optional(:ntpsrv) => [:inet.ip_address()],
  optional(:wins) => String.t(),
  optional(:lease) => non_neg_integer(),
  optional(:serverid) => :inet.ip_address(),
  optional(:message) => String.t(),
  optional(:renewal_time) => non_neg_integer(),
  optional(:rebind_time) => non_neg_integer(),
  optional(:vendor) => String.t(),
  optional(:tftp) => String.t(),
  optional(:bootfile) => String.t(),
  optional(:userclass) => String.t(),
  optional(:tzstr) => String.t(),
  optional(:tzdbstr) => String.t(),
  optional(:search) => String.t(),
  optional(:sipsrv) => String.t(),
  optional(:staticroutes) => [:inet.ip_address()],
  optional(:vlanid) => String.t(),
  optional(:vlanpriority) => non_neg_integer(),
  optional(:pxeconffile) => String.t(),
  optional(:pxepathprefix) => String.t(),
  optional(:reboottime) => String.t(),
  optional(:ip6rd) => String.t(),
  optional(:msstaticroutes) => String.t(),
  optional(:wpad) => String.t()
}