anchor.diff:  
   %% Handle the message by hitting the packet cache and either
   %% using the cached packet or continuing with the lookup process.
  +%%
  +%% If the cache is missed, then the SOA (Start of Authority) is discovered here.
   handle_message(Message, Host) ->
     case erldns_packet_cache:get(Message#dns_message.questions, Host) of
       {ok, CachedResponse} ->
  
positive.code:       handle_packet_cache_miss(Message, get_authority(Message), Host) % SOA lookup
    end.
  
  %% If the packet is not in the cache and we are not authoritative, then answer
  %% immediately with the root delegation hints.
  handle_packet_cache_miss(Message, [], _Host) ->
    case erldns_config:use_root_hints() of
        true ->
  
negative.code:   end;
  
  %% The packet is not in the cache yet we are authoritative, so try to resolve
  %% the request. This is the point the request moves on to the erldns_resolver
  %% module.
  handle_packet_cache_miss(Message, AuthorityRecords, Host) ->
    safe_handle_packet_cache_miss(Message#dns_message{ra = false}, AuthorityRecords, Host).
  
  