{lib, ...}: let
  hostnameIPv4 = {
    "sqbuilds" = "10.1.1.50";
    "dns" = "10.1.2.3";
    "metrics" = "10.1.2.5";
    "proxy" = "10.1.2.10";
    "auth" = "10.1.2.12";
    "cloud" = "10.1.2.15";
    "social" = "10.1.2.17";
  };
  getIPv4 = hostName: hostnameIPv4.${hostName};
in {
  # hostname.home.arpa = ip
  hostnameDNSEntries =
    lib.attrsets.mapAttrs'
    (name: value: lib.attrsets.nameValuePair (name + ".home.arpa") value)
    hostnameIPv4;
  getIPv4 = getIPv4;
}