On Wed, Jul 20, 2016 at 9:40 AM, 延志伟 <yzw_ip...@163.com> wrote:
> Hi, Ralf, I understand prefetch by the recursive server and it is the > common case. > [https://tools.ietf.org/html/draft-liu-dnsop-dns-cache-00] > But if recursive server asks: give me the a RR and all the related RRs > under your domain. And the authoritative server sends back the requested > domain name RR and the related RRs under its domain. It can also improve > the efficiency. > Zhiwei Yan > > 在 2016-07-20 20:48:07，"Ralf Weber" <d...@fl1ger.de> 写道： > >Moin! > > > >On 20 Jul 2016, at 14:36, 延志伟 wrote: > >> But anyway, let's go back to the scenario considered by our draft to > >> illustrate its necessity. > >> I show an example as following (although I think we have described it > >> several times. :-)): > >> In order to visit the www.baidu.com, the user has to query > >> www.baidu.com and many other related domain names > >> (for many related resources such as images, java script, html, flash, > >> video, sound), then a series of queries happen as the attached figure > >> shows. > >So what. If your recursive resolver is used by many people these records > >will be in the cache. There will be no gain. Now of course if your > >resolver only serves you that might be the case, but that is not the way > >DNS was designed or is operated today. Oh and your example have out of > >zone queries (also very common like facebook.com asking for fbcdn.com) > >that can not be solved by this anyway. There is no better tool than a > >prefetching hot resolver for lots of users to solve this problem. > > > >So long > >-Ralf > > > Some thoughts: With CDN's answering based on location, are they using very short TTL's, and thus the cache goes 'cold' quite frequently? And even if users of large pre-fetching resolvers are not helped, what if it helps users of smaller non-pre-fetching resolvers? -- Bob Harold
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