XPost: comp.mobile.android, alt.os.linux, alt.comp.os.windows-10   
   From: robin_listas@es.invalid   
      
   On 2017-04-18 18:28, Char Jackson wrote:   
   > On Tue, 18 Apr 2017 10:51:40 +0200, "Carlos E.R."   
   >  wrote:   
   >   
   >> On 2017-04-18 07:44, Char Jackson wrote:   
   >>> On Tue, 18 Apr 2017 02:22:24 +0200, "Carlos E.R."   
   >>>  wrote:   
   >>>   
   >>>> On 2017-04-17 18:33, Mark Lloyd wrote:   
   >>>>> On 04/17/2017 08:56 AM, Pascal Hambourg wrote:   
   >>>>>   
   >>>>> [snip]   
   >>>>>   
   >>>>>> A DNS cache server is a DNS server. What do you mean ?   
   >>>>>   
   >>>>> I suppose the difference here is does it just cache data from a remote   
   >>>>> NS server, of does it provide local DNS as well. In my case, I want DNS   
   >>>>> requests for "gary.lan" to return 192.168.1.19 (The local IP for my LAN   
   >>>>> web server).   
   >>>>   
   >>>> Exactly.   
   >>>>   
   >>>> A DNS that is not configurable, that you can not add your own entries to   
   >>>> it. That simply queries an outside server (usually one on the ISP,   
   >>>> dynamically selected when the router sets up the connection with the   
   >>>> ISP), and which caches the responses for at least some limited time.   
   >>>>   
   >>>> No, not caching any queries is absurd. Home devices could be directed to   
   >>>> query directly the outside DNS server instead and save power in the   
   >>>> router; it would be as fast and use the same network resources.   
   >>>>   
   >>>> They bother to place a DNS daemon in a router that has little resources   
   >>>> precisely because they want to reduce the load on the ISP DNS.   
   >>>   
   >>> I don't think router designers care that much about ISP DNS. A DNS   
   >>> resolver located locally, within the gateway router, *should* be faster   
   >>> than a DNS located either within the ISP or elsewhere on the Internet,   
   >>> although what's a few milliseconds among friends.   
   >>   
   >> They do care, because those routers are installed "free" by the ISPs,   
   >> and the default configuration is defined by the ISP. So either they are   
   >> built to spec from the ISP, or the ISP chooses one that is appropriate   
   >>from those available.   
   >   
   > OK, I see what you mean. In my experience, the vast majority of routers   
   > found in homes were not supplied by the ISP, but it sounds like your   
   > experience might differ.   
      
   Ah, I see, you say that you often have to buy them. Yes, that's different.   
      
   >   
   >> No, those DNS servers can never be faster than one outside (for a non   
   >> cached query), because they always ask the same DNS server outside to do   
   >> the query; they don't query the DNS chain outside from the roots and up.   
   >> If the answer is cached it will be instant, if not, it has to wait for   
   >> the ISP DNS to find out the answer and reply.   
   >   
   > Fine, but I see what you did there; you qualified it with "for a non   
   > cached query". I agree that non-cached queries aren't helped by having a   
   > local resolver, but non-cached queries very often get followed by cached   
   > queries in actual practice, so there should still be some benefit (until   
   > the TTL expires).   
      
   Correct. They try to also aggregate queries from other computers at the   
   same home.   
      
   But those caches would be irrelevant if the operating systems used at   
   homes by default did caching of their own.   
      
   --   
   Cheers, Carlos.   
      
   --- SoupGate-Win32 v1.05   
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