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--></style></head><body lang=DE link=blue vlink="#954F72"><div class=WordSection1><p class=MsoNormal>Hi Paul,</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>thank you very much for your Statement!</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I am not that Deep into DNS logics so most likely not a very good communication Partner when the Topic becomes that complex <span style='font-family:"Segoe UI Emoji",sans-serif'>😊</span> I am using Unbound for my home Network only, there I think theoretical numbers like „hundreds cache misses per second“ are not that realistic. But I totally agree that making such a feature generic, this is something that Needs to be taken care of.</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Maybe a solution can be to integrate a Sub layer inbetween the local Cache and external resolvers, a shared Cache. This shared Cache is updated by all Peers when a query gets resolved and every peer can ask the shared Cache for entries when local Cache does not deliver any results. Shared Cache instances are then automatically synchronized.</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Obviously this Topic is not an easy one and it seems that there is Nothing in place I can reuse.</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Thanks again!</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Bye</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Gesendet von <a href="https://go.microsoft.com/fwlink/?LinkId=550986">Mail</a> für Windows 10</p><p class=MsoNormal><o:p> </o:p></p><div style='mso-element:para-border-div;border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal style='border:none;padding:0cm'><b>Von: </b><a href="mailto:paul@redbarn.org">Paul Vixie</a><br><b>Gesendet: </b>Montag, 10. Februar 2020 12:11<br><b>An: </b><a href="mailto:unbound-users@lists.nlnetlabs.nl">unbound-users@lists.nlnetlabs.nl</a><br><b>Cc: </b><a href="mailto:talk.about@gmx.de">Talkabout</a><br><b>Betreff: </b>Re: Unbound - Shared Cache</p></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>On Monday, 10 February 2020 09:54:44 UTC Talkabout via Unbound-users wrote:</p><p class=MsoNormal>> I am using unbound on 2 different Servers (also populated bia DHCP as 2</p><p class=MsoNormal>> different Name Servers) and would like to make sure that if one Server</p><p class=MsoNormal>> already answered a query and cached it, the other does not Need to do the</p><p class=MsoNormal>> same query to the Internet again. ...</p><p class=MsoNormal>> Question is, if there is a standard way of doing this or any suggestions</p><p class=MsoNormal>> About the „best“ solution. Maybe somebody already has something like this</p><p class=MsoNormal>> working?</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>this question has come up every year or so. one thing to know is that if this </p><p class=MsoNormal>is a good idea, then it would be a good multi-vendor idea, not just for </p><p class=MsoNormal>unbound, though unbound has a track record of doing things first that turn out </p><p class=MsoNormal>to be good ideas and end up standardized in DNS itself in some form.</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>some open questions that relate to discard policy:</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>if you had hundreds of cache misses per second which ones would you share with </p><p class=MsoNormal>your peer recursive nameservers? (maybe only share it after its first reuse? i </p><p class=MsoNormal>think the opendns anycast network uses a DHT for this, to inform peers of </p><p class=MsoNormal>availability of data, so it can be fetched from a peer if it's needed.)</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>if your peer is sharing hundreds of cache misses per second with you, would </p><p class=MsoNormal>you ever discard something from your own cache to make room for something from </p><p class=MsoNormal>theirs? (generally this isn't the right thing, so you'd give your cache two </p><p class=MsoNormal>LRU quotas, one for your own cache misses, one for those shared to you.)</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>when running at quota, and needing to discard something because a peer just </p><p class=MsoNormal>told you some new thing and you don't have room for N+1, would you choose </p><p class=MsoNormal>least recently learned (LRL) rather than least recently used (LRU) because </p><p class=MsoNormal>when things are used they've move from your peer-cache to your own-cache?</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>other open questions:</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>when using ECS, how do you know which cache additions to share, if your peer </p><p class=MsoNormal>or your peer's stubs don't have the same topology as you/yours do?</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>would you rate limit the feed to a peer so as not to flood their capacity?</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>this is a fascinating topic, as i hope you'll agree.</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>-- </p><p class=MsoNormal>Paul</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>