<HTML dir=ltr><HEAD><TITLE>Re: [Dnsmasq-discuss] Is there an "all-servers" parameter for downstream servers?</TITLE>
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<DIV dir=ltr><FONT face=Arial color=#000000 size=2>Hi Simon,</FONT></DIV>
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<DIV dir=ltr><FONT face=Arial size=2>I assume that your choice of 2) is because flooding servers downstream is safer than flooding servers upstream, and I agree with that. There would be another option which would be creating a new parameter (--all-downstream-servers) to activate the behaviour, although I understand that it could require more code to be developed and tested.</FONT></DIV>
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<DIV dir=ltr><FONT face=Arial size=2>I'm happy with any route you decide to take. Would you have an estimation on how long would it take to add and release this functionality? No pressure at all, of course, I'll plan around it.</FONT></DIV>
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<DIV dir=ltr><FONT face=Arial size=2>Kind regards,</FONT> </DIV>
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<DIV><FONT face=Arial size=2><STRONG>Alberto Cuesta-Canada</STRONG></FONT></DIV></DIV>
<DIV><FONT face=Arial size=1>GaaS Team Lead</FONT></DIV>
<DIV><FONT face=Arial size=1>Excelian Ltd.</FONT></DIV>
<DIV><FONT face=Arial size=1>+44 (0) 7942633361</FONT></DIV></FONT></DIV></DIV>
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<FONT face=Tahoma size=2><B>From:</B> Simon Kelley [mailto:simon@thekelleys.org.uk]<BR><B>Sent:</B> Mon 26/04/2010 16:50<BR><B>To:</B> Alberto Cuesta-Canada<BR><B>Cc:</B> dnsmasq-discuss@lists.thekelleys.org.uk<BR><B>Subject:</B> Re: [Dnsmasq-discuss] Is there an "all-servers" parameter for downstream servers?<BR></FONT><BR></DIV>
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<P><FONT size=2>Alberto Cuesta-Canada wrote:<BR>> Hi all,<BR>> <BR>> Is there an "all-servers" parameter for downstream servers?<BR><BR>There is an --all-servers configuration, but it only applies to upstream<BR>servers which don't have a domain. This is an oversight: I don't think a<BR>system which has more than one server for particular domains was<BR>envisaged. This flag is not linked to a particular set of servers, so<BR>setting it would cause the "all servers" behaviour to apply to the<BR>"domainless" servers too. This isn't necessarily good.<BR><BR>As you noticed, the behaviour of servers-with-domains is different to<BR>domainless servers. dnsmasq remembers which domainless server it used<BR>last and continues to use that whilst is can, for domains-with-servers,<BR>it always starts with the same server.<BR><BR>I can see three possible solutions.<BR><BR>1) Make --all-servers apply to servers-with-domains as well as<BR>domainless ones.<BR>2) Provide all-servers behaviour for servers-with-domains automatically<BR>without having to set --all-servers.<BR>3) Provide the complete remember-last-server for functionality for<BR>servers-with-domains.<BR><BR><BR>I think I prefer 2)<BR><BR><BR>Simon.<BR><BR>> <BR>> I have a configuration with three DNS domains, each one served by two<BR>> dnsmasq servers (complete description at the end).<BR>> <BR>> I'm trying to set up a redundant structure, with cron jobs that ensure<BR>> that both DNS servers for each domain are identical, so if one fails,<BR>> the other will serve the requests. All the machines under my control<BR>> repeat the query in rapid sucession if it doesn't come immediately<BR>> answered, and the DNS servers seem to understand that so the behaviour<BR>> is that any query from a machine in my domain reaches all dns servers in<BR>> the network and it is always answered, regardless of which machines are<BR>> down. For the size of my systems this is fine, it doesn't matter if it<BR>> is unefficient.<BR>> <BR>> The problem I have is that the corporate servers don't work that way. We<BR>> have three of them, and when a machine outside my domains makes a query,<BR>> all of them are queried and route to one of my main<BR>> servers. Unfortunately they always ask to the first one, and never<BR>> repeat the query. The round-robin protocol seems to reset for each<BR>> query, so my main servers only ask the primary servers downstream, fail,<BR>> and the corporate servers return (and cache) a failure, thus rendering<BR>> my failover structure useless for other domains.<BR>> <BR>> This could be solved modifying the configuration on the corporate server<BR>> (politics!), or instructing the my main dns servers to always route<BR>> queries to all servers downstream, and to serve the first result coming<BR>> up. It's the same as using "all-servers", but downstream.<BR>> <BR>> Here is a small diagram (use monospace to see it):<BR>> <BR>> CORPORATE 172.30.0.1 (corporate.local)<BR>> 172.30.0.2<BR>> 172.30.1.1<BR>> ||<BR>> || *.mydomain.local<BR>> ||<BR>> MAIN 192.168.0.250 (main.mydomain.local)<BR>> 192.168.0.251<BR>> || ||<BR>> sub1.mydomain.local || || sub2.mydomain.local<BR>> || ||<BR>> SUB1 192.168.1.250 192.168.2.250 SUB2<BR>> 192.168.1.251 192.168.2.251<BR>> <BR>> server=/sub1.mydomain.local/192.168.1.250<BR>> server=/sub1.mydomain.local/192.168.1.251<BR>> server=/sub2.mydomain.local/192.168.2.250<BR>> server=/sub2.mydomain.local/192.168.2.251<BR>> <BR>> Many thanks,<BR>> <BR>> *Alberto Cuesta-Canada*<BR>> GaaS Team Lead<BR>> Excelian Ltd.<BR>> +44 (0) 7942633361<BR>><BR>> The information contained in this email and any attached files are<BR>> confidential and intended solely for the addressee(s). 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Unless otherwise<BR>> stated, this email message is not intended to be contractually binding.<BR>> Where an Agreement exists between our respective companies and there is<BR>> conflict between the contents of this email message and the Agreement<BR>> then the terms of that Agreement shall prevail.<BR>><BR>> Excelian<BR>> 50 Featherstone Street<BR>> London<BR>> EC1Y 8RT<BR>> Tel: +44 (0) 20 7336 9595<BR>> Fax: +44 (0) 20 7336 9596<BR>> www.Excelian.com<BR>> _____________________________________________________________________<BR>> This e-mail has been scanned for viruses by MessageLabs. For further<BR>> information visit <A href="http://www.messagelabs.com/">http://www.messagelabs.com</A><BR>><BR>> Excelian subscribes to cleaner and greener methods of working. Help take<BR>> responsibility for the environment. Please don't print this email unless<BR>> you absolutely have to.<BR>><BR>><BR>> ------------------------------------------------------------------------<BR>><BR>> _______________________________________________<BR>> Dnsmasq-discuss mailing list<BR>> Dnsmasq-discuss@lists.thekelleys.org.uk<BR>> <A href="http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss">http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss</A><BR><BR></FONT></P></DIV><BR>
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