anchor.diff:          end
       end, [], NameServers).
   
  +%% @doc This function takes a list of nameservers, finds it's A/AAAA record in the given record set
  +%% and returns the nameserver's IP address.
  +%% @end
  +-spec get_ips_for_notify_set([dns:rr()], [dns:rr()]) -> [inet:ip_address()].
   get_ips_for_notify_set(Records, NotifySet) ->
       get_ips_for_notify_set(Records, NotifySet, []).
   
  
positive.code:             remove_old_soa_add_new(NewAuthority, Records, [NewAuthority | NewRecords]);
          _ ->
              remove_old_soa_add_new(NewAuthority, Records, [Record | NewRecords])
      end.
negative.code:             get_notify_set(Tail, SOA, NameServers)
      end.
  
  %% @doc Takes an SOA, and a list of nameservers and returns a list of nameservers that are not
  %% include in the SOA's mname field.
  %% @end
  -spec exclude_mname_duplicates(dns:rr(), [dns:rr()]) -> [dns:rr()].
  exclude_mname_duplicates(SOA, NameServers) ->
      MName = SOA#dns_rrdata_soa.mname,
      lists:foldl(fun(NameServer, Acc0) ->
  