anchor.diff:      %%
       #dns_rr{ttl = TTL, tm = TM, cnt = Cnt} = RR,
       if
  -        TTL =:= 0 ->
  -            %% Valid, immediately expired; return and delete
  -            Key = match_rr_key(RR),
  -            match_rr(
  -              CacheDb, RRs, Time,
  -              ResultRRs#{Key => RR}, InsertRRs, [RR | DeleteRRs]);
           TM + TTL < Time ->
               %% Expired, delete
               match_rr(
  
positive.code:       {add_rrs,
         [RR#dns_rr{
            bm = tolower(RR#dns_rr.domain), tm = TM, cnt = TM}
          || RR <- RRs]}).
  
  %%
  %% getbyname (cache version)
  
negative.code: %%
  %% Look up all matching objects.  The still valid ones
  %% should be returned, and updated with a new cnt time.
  %% All expired ones should be deleted.
  %%
  match_rr(MatchRR) ->
      CacheDb = inet_cache,
  